Abstract: In a fractional distillation column, a desired ratio between the flow rate of a side draw product stream and the internal reflux flow rate at the particular tray from which a side draw stream is withdrawn from the fractional distillation column is maintained by manipulating the flow rate of the center reflux stream so as to maintain the desired ratio between the internal reflux flow rate and a side draw product stream flow rate at the particular tray from which the side draw stream is withdrawn from the fractional distillation column. Control of the ratio between the flow rate of a side draw product stream and the internal reflux flow rate results in an improved side draw product stream purity.

Abstract: In a fractionation distillation process in which a pump around stream and an external reflux are utilized to control heat removal from an upper portion of the fractional distillation column and in which the pump around stream is utilized to preheat the feed stream flowing to the fractional distillation, the flow rate of the pump around stream is manipulated so as to substantially maximize the flow rate of the pump around stream while maintaining a desired heat removal from the fractional distillation column. Priority control of the pump around stream and external reflux result in a maximum preheating of the feed stream flowing to the fractional distillation column which improves the energy efficiency of the fractional distillation process.

Abstract: A batch distillation operation is automatically controlled from a start-up mode to a shut-down mode.

Abstract: A control system for a fractional distillation column, where the feed to the fractional distillation column is supplied from at least one separator, is disclosed in which overloading of the fractional distillation column is prevented by monitoring a control parameter associated with the fractional distillation column which indicates that the fractional distillation column is being overloaded. The flow of the feed from the at least one separator is manipulated to maintain the control parameter which indicates that the fractional distillation column is being overloaded within desired limits. The feed to the at least one separator is manipulated to maintain the liquid level in the at least one separator within desired limits.

Abstract: In a fractionation process in which at least two fractional distillation columns are cascaded in series, the vapor from the overhead accumulator associated with the first fractional distillation column in the series is provided to a feed tank for the second fractional distillation column in the series. The flow of the vapor from the overhead accumulator associated with the first fractional distillation column in the series is controlled by means of a control valve. An interactive control system is utilized to maintain the pressure in the overhead accumulator associated with the first fractional distillation column within safe operating limits, maintain the control valve at a substantially fully open position so as to minimize the pressure drop across the control valve controlling the flow of vapor from the overhead accumulator associated with the first fractional distillation column, and maintain the pressure in the feed tank to the second fractional distillation column at a desired value.

Abstract: In a fractionation distillation process in which a pump around stream and an external reflux are utilized to control heat removal from an upper portion of the fractional distillation column and in which the pump around stream is utilized to preheat the feed stream flowing to the fractional distillation, the flow rate of the pump around stream is manipulated so as to substantially maximize the flow rate of the pump around stream while maintaining a desired heat removal from the fractional distillation column. Priority control of the pump around stream and external reflux result in a maximum preheating of the feed stream flowing to the fractional distillation column which improves the energy efficiency of the fractional distillation process.

Abstract: A control system for a fractional distillation column in which a pumparound stream is used to remove heat from the fractional distillation column is disclosed. A combination of feedforward and feedback control is utilized to control the heat removal by the pumparound stream in such a manner that smoother operation of the fractional distillation column will be accomplished and a closer approach to required product specifications will be approached.

Abstract: A non-linear level controller is provided in which the proportional term is a function of the actual liquid level in a vessel compared to the actual liquid level in the vessel at a previous time. The integral term is a function of the actual liquid level in the vessel compared to a set point which is representative of the desired liquid level in the vessel. Both the proportional term and the integral term are modified by a variable gain factor which is a non-linear function of the liquid level being controlled. The proportional term and integral term are combined to provide the controller output which is utilized to manipulate a flow of liquid from the vessel in which the liquid level is being controlled.

Abstract: Apparatus is disclosed for treating pickling solutions used for pickling metal, such as iron, steel, special alloys, or the like. In a preferred embodiment, the apparatus includes an evaporator, a condensor, a crystallizer, a crystal-separating device, fittings and conduits for connection to the metal-treating plant, and a device for automatically controlling the evaporation rate in the evaporator. The evaporator includes a flow channel, vapor removal connection above the liquid level in the flow channel, an inlet and outlet for the solution being treated, and a plurality of electrodes for directly applying AC current to the solution. The electrodes are mounted spaced along the length of th flow channel and are completely covered by the solution so as to be out of contact with the vapor. The crystallizer comprises an upright cylindrical vessel having an inlet and an outlet, a driven shaft extending in the center line of the vessel, and is provided with radial ribs.

Abstract: In a fractionation process in which at least two fractional distillation columns are cascaded in series, the vapor from the overhead accumulator associated with the first fractional distillation column in the series is provided to a feed tank for the second fractional distillation column in the series. The flow of the vapor from the overhead accumulator associated with the first fractional distillation column in the series is controlled by means of a control valve. An interactive control system is utilized to maintain the pressure in the overhead accumulator associated with the first fractional distillation column within safe operating limits, maintain the control valve at a substantially fully open position so as to minimize the pressure drop across the control valve controlling the flow of vapor from the overhead accumulator associated with the first fractional distillation column, and maintain the pressure in the feed tank to the second fractional distillation column at a desired value.

Abstract: A control system for a fractional distillation column, where the feed to the fractional distillation column is supplied from at least one separator, is disclosed in which overloading of the fractional distillation column is prevented by monitoring a control parameter associated with the fractional distillation column which indicates that the fractional distillation column is being overloaded. The flow of the feed from the at least one separator is manipulated to maintain the control parameter which indicates that the fractional distillation column is being overloaded within desired limits. The feed to the at least one separator is manipulated to maintain the liquid level in the at least one separator within desired limits.

Abstract: A fractionation column is provided with a feed inlet and three product outlets, with the product outlets including an overhead vapor outlet, a bottoms liquid outlet and a side draw outlet. A plurality of vertically spaced apart vapor-liquid contact trays are mounted in the column. A generally vertical partition is positioned within the column in a central region between an upper and a lower vapor-liquid contact tray and divides the central region into first and second chambers defined by the upper and lower trays, column shell and partition. The feed inlet opens into the first chamber while the side draw outlet opens into the second chamber. First control means is provided for controlling the various inputs and outputs of the column. Second control means is also provided for measuring various constituent portions of fluid mixtures within the column.

Abstract: A control system is provided for a fractional distillation column where at least a portion of the overhead vapor stream from the fractional distillation column is utilized in a refrigeration and heating system for a process with which the fractional distillation column is associated. The liquid level is an overhead accumulator associated with the fractional distillation column is maintained at a level sufficient to insure that a sufficient supply of the overhead vapor stream from the fractional distillation column is available to supply the refrigeration and heating needs of the process with which the fractional distillation column is associated.

Abstract: A hydrocarbon stream comprising C.sub.2 to C.sub.8 hydrocarbons is stripped at a high temperature to allow passage of the stripper bottoms stream into a reaction zone without further heating, and the effluent of the reaction zone is then heat exchanged against the feed stream to the stripper column to recover heat. Operation of the reaction zone at the desired temperature is achieved by adjusting the amount of the stripper bottoms stream which is split off for cooling by heat exchange against the feed to the stripper column. The cooled split-off portion is then admixed with the remaining high temperature portion. Adjusting the flow rate of the portion of hot reaction zone effluent which is heat exchanged against the stripper feed stream is performed to control either the temperature of the stripper feed stream or the temperature of the reaction zone effluent as it is passed to a downstream operation.

Abstract: The flow rate of feed material containing a constituent to be absorbed and the flow rate of the absorption medium entering an absorption zone are controlled in response to the content and flow rate of feed material entering the absorption zone and the amount of a desired bottoms constituent in the overhead stream of the absorption zone so that the efficiency of the absorption process is optimized. Under circumstances necessitating maximum production from the absorption zone and its associated stripping zone, the absorption medium flow rate is maintained at a maximum value and the feed flow rate is controlled in response to feed composition and flow as well as the concentration of desired bottom product in the overhead stream. The output of the absorption unit is stabilized by alteration of the flow control apparatus associated with the output stream of the stripping zone in order to alter the amount of control over the output flow.

Abstract: A vapor generating and recovering apparatus including vapor condenser control means wherein one component is separated from a second component of a liquid solution by vaporization and then recovered by condensing including at least one chamber for vaporizing the first component from the liquid solution and a second chamber for recovering the vapor, the vapor generating chamber being in heat emitting relation with a heat emitting means and the vapor recovering chamber being in heat abosrbing relation with a heat absorbing means, the heat absorbing means including a temperature sensing device at a preselected position within the second chamber to control the vapor level of the vaporized component, the sensing device actuating a cooling fluid which is included within the heat absorbing means whereby the vapor level in the apparatus is controlled by the temperature sensing device in combination with the heat absorbing control means.

Abstract: A hydrocarbon stream comprising benzene is stripped at a high temperature to allow passage of the stripper bottoms stream into a clay treating zone without further heating, and the effluent of the clay treating zone is then exchanged against the feed stream to the stripper column to recover heat. Operation at the optimum clay treating temperature is achieved by adjusting the amount of the stripper bottoms stream which is split off for cooling by heat exchange against the feed to the stripper column. The cooled split-off portion is then admixed with the remaining high temperature portion. Adjusting the flow rate of the portion of hot clay treater effluent which is heat exchanged against the stripper feed stream is performed to control the temperature of either the stripper feed stream or the temperature of the clay treater effluent as it is passed into a downstream fractionator.

Abstract: The steam which develops during water cooling of a furnace is withdrawn from the cooling system of the furnace, introduced into a distillation plant wherein it is subjected to at least partial condensation, and the thus-obtained condensate is recirculated into the cooling system of the furnace. An apparatus for carrying out the method is also disclosed.

Abstract: A method for regulating, or controlling heat input to the reboiler section of a fractionation column. Flow-measuring means, disposed in a substantially liquid-free environment within the confines of the reboiler section, produces a signal which is representative of the quantity of vapor flowing from the reboiler section upwardly into the fractionation section. This signal is transmitted to heat-varying means, whereby fuel input to an external reboiler heater is regulated in response to the quantity of vapor flow.

Abstract: Heat balance of a fractionation column is controlled and maintained by obtaining three differential temperatures between selected temperature-sensing points along the height of the column. A signal representing one of the delta-T's is employed in regulating the quantity of reflux returned to the rectification zone. The remaining two delta-T's are conjunctively utilized to regulate the enthalpy (heat-input content) of the reboiled liquid bottoms stream being returned to the reboiler section of the column. With respect to the latter, a selected one of the two delta-T signals is multiplied by a multiplier representing the ratio of the number of trays between the temperature sensing points supplying the non-selected delta-T signal to the number of trays between the temperature sensing points supplying the selected delta-T signal.

Abstract: Control of a fractionation column is maintained by obtaining two differential temperatures between pairs of selected temperature-sensing points along the height of the column. One pair of temperature sensors is vertically-spaced above the feed tray, while the second pair is below the feed tray. Signals representing the sensed and measured delta-T's are employed in conjunction with a signal representing the flow rate of the feed stream in regulating the quantity of reflux to the rectification zone and in maintaining the required reflux to feed ratio.

Abstract: Heat balance of a fractionation column is controlled and maintained by obtaining three differential temperatures between selected temperature-sensing points along the height of the column. Signals representing the three delta-T's are employed in regulating the quantity of reflux to the rectification zone and the enthalpy (heat-input content) of the reboiled liquid bottoms stream. With respect to the latter, two delta-T's, obtained below the feed locus are used. One of these is considered in conjunction with the third delta-T, obtained above the feed tray, and an additional signal representing the flow rate of the feed stream, to regulate the quantity of reflux.

Abstract: Heat balance of a fractionation column is maintained through the utilization of differential temperature sensors located at selected points in the height of the column. Signals representative of three delta-T's are employed in regulating the quantity of reflux to the rectification zone and the enthalpy (heat-input content) of the reboiled liquid bottoms stream. With respect to the former, two differential-temperature signals are used; these result from four temperature sensors vertically-spaced along virtually the entire height of the fractionation column.

Abstract: A hydrocarbon stream comprising benzene is stripped at a high temperature to allow passage of the stripper bottoms stream into a clay treating zone without further heating, and the effluent of the clay treating zone is then exchanged against the feed stream to the stripper column to recover heat. Operation at the optimum clay treating temperature is achieved by adjusting the amount of the stripper bottoms stream which is split off for cooling by heat exchange against the feed to the stripper column. The cooled split-off portion is then admixed with the remaining high temperature portion.

Abstract: A control method and system for regulating the heat input to the reboiler section of a distillation column having attendant thereto a first external heat-recovery reboiler. Flow-measuring means, disposed within a substantially liquid-free environment, produces a signal which is representative of the quantity of vapor flowing from the reboiler section upwardly into the fractionation section of the column. This signal is transmitted to heat-varying means whereby the heat input to a second external reboiler heater is regulated in response to the quantity of vapor flow.

Abstract: A vapor generating and recovering apparatus for separating one component from a second component of a liquid solution and recovering the first component including at least one chamber for generating vapor from the liquid solution and recovering the vapor in a liquid form, the vapor generating portion of the chamber being in heat emitting relation with a heat emitting means and the vapor recovering portion chamber being in heat absorbing relation with a heat absorbing means. A preferred system for providing heat to the vapor generating portion of the chamber and removing heat from the vapor recovering portion of the chamber is a refrigerating system which includes condensing coils and evaporating coils in heat transfer relation with the vapor generating and vapor recovery chamber.

Abstract: Automatic regulation system for a distillation unit including a charging vessel, provided with heating means, surmounted by a distillation column overtopped by a condenser, a withdrawing system and recovery tanks, said system comprising an intermediate tank between the withdrawing system and the recovery tanks, means for controlling the liquid level in said intermediate tank and the discharge of liquid therefrom into the recovery tanks, valve means for applying at will a reduced pressure or the atmospheric pressure to the distillation unit and the intermediate tank and means for changing the recovery tanks in synchronization with the actuation of said valve means.

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: A method and apparatus for the separation of a normally liquid stream comprising low, high and intermediate volatility components by distilling the feed stream in a distillation zone, removing a vaporous overhead stream comprising the high volatility components together with some of the intermediate volatility component, removing from a central portion of the zone a vaporous side stream consisting essentially of the intermediate volatility component, the rate of removal of the intermediate volatility component being controlled by the liquid level of the intermediate volatility component condensed from the overhead stream and contained in a reservoir.