Abstract: A process for the multi-stage condensation of an overhead fraction is disclosed. The process facilitates optimal response to changes in distillation column controls wherein column top reflux condensation is preferentially returned to said distillation column, but auxiliary surge capacity is obtained by connection to a first accumulator section of an accumulating zone, which surge capacity is supplemented by one-way flow of liquid from a cooler, second section in said accumulation zone.

Abstract: This invention relates to a solar still wherein the evaporation takes place in partially evacuated tubings which are heated by sunlight. The water to be distilled is supplied from a reservoir vessel which is sealed off after batch loading. The reservoir vessel is elevated above the solar collector. The water is fed into the heater tubings routed through the solar collector by gravity, through an orifice and a heat exchanger-condenser. The steam tubing branches off from the heater tubing in the solar collector vertically, and is routed through the heat exchanger-condenser. At this end, it is connected to a vertical tubing of a sizable length that empties into the distilled water reservoir. The exit end of the heater tubing routed through the solar collector is connected to another vertical tubing of a sizable length that empties into an overflow tank.

Abstract: The invention provides a compact automatically operating distillation apparatus comprising a baseplate that will free-stand, but is more usually located on a reservoir to receive the distillate, which usually is water. A boiler container having an electric heater is removably mounted on a support, which is movably mounted on the baseplate with the weight of the container and the water opposed by a spring. The support operates electric switches that open a solenoid-operated valve to supply water to the boiler when its weight decreases a predetermined amount, and that will switch off the heater if the boiler has insufficient water. The output of the boiler goes to a condenser coil which is supplied with cooling air by a fan. A float in the reservoir controls another switch that will stop operation when the reservoir is full.

Abstract: A process for controlling a distillation column in which feed liquid supplied thereto is heated by heating steam comprises the steps of: controlling the steam flow rate so that the steam flow rate is increased in response to the difference between the temperature measured at the bottom of a calculated column and the temperature of boiling point of the feed liquid until the former temperature exceeds the latter temperature when the former is not higher than the latter; controlling the steam flow rate so that the temperature around an intermediate tray falls within a first predetermined temperature range when the temperature measured at the bottom of the column exceeds the calculated temperature of the boiling point of the feed liquid; controlling the steam flow rate so that a reflux ratio is adjusted to within a predetermined reflux ratio range when the temperature around the intermediate tray falls in the predetermined temperature range; and controlling the steam flow rate so that the reflux ratio is maintain

Abstract: The temperature of a crude oil provided from a crude oil preheat furnace to a crude tower is substantially minimized by controlling such temperature so as to maintain a desired minimum overflash flow in the crude tower. Also, the temperature of each of the individual coils in the preheat furnace are balanced with respect to each other. Such minimization and balancing results in substantially optimal utilization of the fuel provided to the preheat furnace which results in considerable economic savings with respect to the operation of the preheat furnace.

Abstract: An automated solar still is disclosed which incorporates a system of valves and other controls that halts production when the level of solar insolation is not adequate to support evaporation, admits water for treatment only when the still requires resupply, operates at nominal pressure by gravity flow and flushes out suspended and dissolved contaminants automatically. Production is halted under conditions of inadequate solar insulation by means of a temperature sensitive valve which is exposed to the received sunlight. In one embodiment, heating and evaporation occur directly in a central chamber. In another embodiment heating occurs in external panels and evaporation occurs from trays in an evaporation chamber. With changes in dimensions and proportions the system of controls may be used in solar stills for desalinating sewater.

Abstract: A control system for use in a condensation heating facility to control the secondary vapor blanket used to prevent loss of primary vapor. The control system includes a pair of secondary vapor sensors which detect a secondary vapor blanket slightly below and alternatively slightly above a design depth. The sensors are connected to control relays which energize a high rate dispensing pump to build the secondary vapor blanket when it is below the low depth and to energize a low rate dispensing pump when the secondary vapor blanket is between the low depth and the high depth. Additional control is arranged to inhibit dispensing of secondary liquid when the secondary vapor blanket is above the high depth or the primary vapor blanket is below its designed depth or finally during a vapor phase heating cycle where the primary and secondary vapor blankets collapse as a function of heating during the cycle.

Abstract: A measurement of the pressure in a fractional distillation column is utilized to bias the desired external reflux flow rate which is determined by some conventional method. The bias is applied only when a pressure limitation is exceeded and the external reflux flow rate is reduced as a result of the bias which results in a reduction of column pressure.

Abstract: The Reid Vapor Pressure of a hydrocarbon mixture consisting essentially of hydrocarbons selected from the same series is determined based on the actual temperature and vapor pressure of the hydrocarbon mixture. The thus determined Reid Vapor Pressure may be compared to a set point for the Reid Vapor Pressure with the results of the comparison being utilized to maintain the actual Reid Vapor Pressure substantially equal to the desired Reid Vapor Pressure.

Abstract: A pure water tank for distillation equipment comprises a casing on a water tank proper and a communicating pipe via which interiors of the casing and tank proper communicate each other. Water in the casing prevents air from entering into the pure water tank through a condenser when generation of steam is halted.

Abstract: An oven for heating a distillable material in a preselected gas atmosphere. The oven comprises an inner heating chamber adapted to receive a spherical gravity lid, the heating chamber being connected to and in communication with a gas exhaust tube having a condensate trap at the termination thereof. The inner heating chamber is also in communication with and surrounded by an outer gas flow chamber, the outer gas flow chamber having a plurality of heater elements therein. The gas exhaust tube is surrounded by an ante chamber which is in communication with the outer chamber. The heater elements are continuously monitored by a programmable controller and a thermocouple in communication therewith. During oven operation, a purge gas is introduced to the ante chamber and flows therefrom into the outer gas flow chamber around the heater elements and into the top of the inner heating chamber.

Abstract: A vapor distillation system sprays a mixture of liquids to be distilled into an evacuated vaporizer chamber. The low boiling point components of the mixture will be vaporized while the remainder of the mixture will collect at the bottom of the vaporizer chamber. The collected liquid is recirculated and heated. The recirculating liquid is discharged, and fresh mixture is introduced, as a function of the sensed temperature of the recirculating liquid. The vapor is transferred to a condenser chamber having a water spray head so that the chilled spray condenses the vapor. Both the condenser chamber and the vaporizer chamber have fluid level control systems.

Abstract: The overcharge prevention device is installed in a solvent processing plant in a vacuum evaporator of a heat exchanger. It assures that the level of the cleaning solution in the vacuum evaporator cannot randomly rise when a feed valve malfunctions. A float body of an overcharge valve extending into the vacuum evaporator exerts a pressure through a double-arm lever and a valve plunger upon a ball valve and a valve seat in normal operation and holds the overcharge valve in a closed position. As the level of the cleaning solution undesirably rises, the buoyant action of the cleaning solution acts on the float body, causing the pressure on the valve seat to diminish, and the overcharge valve opens. This permits air to enter into the vacuum evaporator through the overcharge valve. The generated vacuum collapses and the suction force employed to ingest the cleaning solution disappears.

Abstract: A desired separation between sidedraw product streams withdrawn from a fractional distillation column is maintained by controlling the flow rate of the external reflux associated with a particular sidedraw product stream in response to the output signal from a temperature controller which is reset by an internal reflux controller. Such cascade control improves the stability of a fractionation process and provides for good control of the separation between sidedraw product streams.

Abstract: In a fractional distillation process in which a sidedraw product stream is withdrawn from the fractional distillation column, the flow rate of the overhead product stream is controlled so as to increase the flow of the upper external reflux so as to drop as much as possible of the overhead product into the sidedraw product stream. However, valve position control is utilized to override the control of the flow of the overhead product stream, which is being controlled so as to substantially maximize the flow of the sidedraw product stream, if the valve controlling the flow of the upper external reflux approaches fully open such that control of the liquid level in the overhead accumulator associated with the fractional distillation process is not lost.

Abstract: A vapor generating and recovering apparatus for vaporizing a liquid and condensing a vapor, the apparatus including a container having a liquid therein with heating and cooling systems in heat transfer relation with the liquid and vapor in the container. The heating and cooling systems include means to vaporize the liquid and means to condense the vaporized liquid disposed within the container. Temperature or pressure sensing means in the cooling system is utilized to shut down the heating system when a preselected vapor level is exceeded.

Abstract: In a fractional distillation process in which it is desired to maintain a desired ASTM end point temperature of the overhead liquid product withdrawn from the fractional distillation process, changes in the heat removed by the fractional distillation process per unit of the feed are utilized to determine the equilibrium flash vaporization initial point and the equilibrium flash vaporization end point temperature for the overhead liquid product. The initial point temperature and end point temperature are then utilized to determine the actual slope of the equilibrium flash vaporization boiling point line. Changes in the slope of the equilibrium flash vaporization boiling point line are utilized to determine the actual slope of the ASTM boiling point curve at any particular time. The actual ASTM end point temperature for the overhead liquid product is derived based on the actual slope of the ASTM boiling point curve thus determined.

Abstract: In a fractional distillation process in which it is desired to maintain a desired overhead product composition and bottoms product composition, a set point for the flow rate of the external reflux to the fractional distillation column is increased or decreased by an incremental amount or is left constant based on whether the concentration by the heavy key component in the overhead product stream and the concentration of the light key component in the bottoms product stream are above a high limit, below a low limit, between the high limit and low limit or some combination thereof and also based on the relationship between a set point for the flow rate of the external reflux and a high limit for the flow rate of the external reflux. At the same time, a temperature set point for the fractional distillation column is increased or decreased by an incremental amount or is left constant depending on the same factors.

Abstract: A vapor compression distillation system for distillation of any two-component liquid mixture where separation of the more volatile from the less volatile component is required. This system achieves a very high efficiency through the use of vapor compression in conjunction with three heat exchangers: a reboiler which condenses the hot vapors compressed by a vapor pump and uses the heat given up by the condensing vapor to boil bottoms liquid to produce vapor within the stripper, a distillate heat exchanger which recovers heat from the distillate stream, and a bottoms heat exchanger which recovers heat from the outgoing bottoms effluent. This particular component configuration and process results in an exceptionally stable and reliable operation requiring the continuous control of only one parameter, reboiler temperature, while fixing all other process variables.

Abstract: An evaporator apparatus (10) and method for converting a contaminated fluid including mostly water and water soluble substances into a vapor and a residue. Apparatus (10) includes a container (11) for retaining the fluid. A heat source (17) is utilized for supplying heat to evaporate the fluid. A flue assembly (18) positioned in the fluid conveys the heat from the heat source (17) through the fluid. A draft mechanism (20) draws off the resulting vapors as they are formed.

Abstract: In a fractional distillation process in which it is desired to maintain a desired overhead product composition and bottoms product composition, a set point for the flow rate of the external reflux to the fractional distillation column is increased or decreased by an incremental amount or is left constant based on whether the concentration of the heavy key component in the overhead product stream and the concentration of the light key component in the bottoms product stream are above a high limit, below a low limit, between the high limit and low limit or some combination thereof. At the same time, a temperature set point for the fractional distillation column is increased or decreased by an incremental amount or is left constant depending on the same factors. Use of these set points for process control provides control of the overhead product composition and bottoms product composition without the use of analysis controllers.

Abstract: This process separates less volatile contaminates from thermal power recovery systems utilizing a volatile working fluid in a cyclic closed system; such a system may comprise a reservoir, a pump, a heater, a separator, a throttle device, a turbine and a condenser. The purification can be accomplished during start-up, shut-down or periods of low power generation. The contaminant is separated from the working fluid in the separator in which the temperature and pressure correspond to a dew-point substantially above that of a sample of uncontaminated working fluid. To achieve this condition, the normal flow of liquid from the reservoir to the heater is reduced and the heater and throttle device are correspondingly adjusted. The condensed contaminant is removed from the separator while substantially all of the working fluid which has been vaporized is passed on through the throttle device to the turbine.

Abstract: A solar desalination system in which fresh water is derived from sea water by focussing solar ray energy from a collecting reflector onto an evaporator tube located at substantially the focal apex of the reflector. The reflector/evaporator tube assembly is mounted on a horizontal open grid platform which may support a plurality of parallel reflector/evaporator tube assemblies. The reflectors may serve as pontoons to support the desalination system unit on a body of sea water. The solar heat generated vapor is condensed in condenser tubes immersed in the sea water. Intermittently sea water concentrate is withdrawn from the evaporator tubes. Velocity of the vapor passing from the evaporator tubes to the condensers may be utilized for generating power.

Abstract: The heat to a feed in a distillation operation is controlled in response to the amount of liquid in a liquid condensate collection means.

Abstract: Apparatus and methods are provided for controlling liquid levels in different vessels, and the blending of different materials in the separation and purification of polymeric materials in solution, such as polyethylene in cyclohexane.

Abstract: A system for treating waste effluent and recovering solids and solvent material including a reservoir mounted on a stand connected by means to a solvent migrator including an adjustable trough for receiving new solution, a secondary reservoir with a cloth or absorbent material designed to contact the fluid in the secondary reservoir, while parallel to the sun's rays, an automatic leveling means and apparatus for recirculation of waste effluent including a leveling ball, and suction tubing for the recirculation of fluid, a solar unit comprised of glass panels to form a collecting dome with collecting troughs and a bonnet to shade the top of the pyramid formed by the dome panels and mirrors for the reflection of sunlight, all of which is connected to a chemical trap and subsequently a collecting means for the pure product.

Abstract: A process and apparatus are provided controlling the heat input of an extractive distillation column. The bottom of the column is heated with a major stream of thermal energy which is either slowly varying in time or controlled by the amount of starting material mixture and with a minor stream of thermal energy which is controlled by sensing the thermodynamic state in the upper half of the column during the process. The major stream can provide about 90 percent and the minor stream about 10 percent of the heat fed to the column. The minor stream can be controlled by the temperature at one point in the upper half of the column, by the temperature difference at two points in the upper half of the column or by gas chromatographic analysis of the extract material concentration near the top of the column. The process allows one to keep a low concentration of the extract material in the raffinate.

Abstract: Distilling equipment comprising input apparatus (21) including a boiling chamber (83) and means (80-82, 104-107, 110, 111) for supplying raw liquid to the boiling chamber at a predetermined level, a closed condensation chamber (22) above the predetermined level and connected to the top of the boiling chamber (96) to receive therefrom only vapor from the raw liquid, and output apparatus (20) including a liquid collection container (25) below the condensation chamber and liquid circulating structure (29-34, 44-55) for withdrawing liquid from the container, cooling the liquid, discharging it within the condensation chamber, and returning it to the container.

Abstract: A continuous trickle-down distillation unit for producing hydrated alcohol having a compact, elongated distillation tube through which a fluid mixture including alcohol as one of its constituents passes. Within the distillation tube only the alcohol-predominant portion of the fluid mixture is vaporized while the remaining constituents of the fluid mixture are removed. The vaporized alcohol-predominant portion is condensed within a chamber which communicates with the distillation tube and is removed therefrom by a collection plate which extends partially into the chamber.

Abstract: The present invention makes use of spent or loaded process liquid at relatively high pressure to power a pump for recirculation of regenerated process liquid for gas contact in a relatively high pressure gas-liquid contact apparatus. In this manner, the power fluid used for recirculation supplies about 65% of the pumping energy requirements and the remaining 35% of the needed pumping energy is supplied by an externally powered pump, such as an electric motor-driven or engine powered pump. In accordance with the present invention, the power end of the fluid-power pump is flooded with liquid at all times so that no free gas is used. The extra volume of liquid used for pumping is regenerated and pumped back to the contactor by an externally powered pump, for example, a plunger-type, electrically-driven or engine-driven pump.

Abstract: Apparatus for condensing vapors at reduced pressure including a cooled vapor condenser having a liquid level sensor therein with a vacuum pump being connected by way of a control valve for drawing vapor from the vapor chamber of the condenser. The liquid level sensor opens and closes the control valve to control drawing of vapor from the vapor chamber in accordance with the level of liquid in the condenser.

Abstract: An apparatus for the distilling and evaporating of sea water so to produce pure fresh water on a large production basis; the apparatus including an evaporator having a baffle system of novel design therein so as to separate evaporated steam from non-evaporated water drops, a duct for conveying the evaporated steam to a condenser and a pure water supply tank; the evaporator being supplied by sea water.

Abstract: A desired cloud point temperature for a side draw product stream from a fractional distillation column is maintained at a desired level by comparing a calculated actual cloud point temperature, which is updated periodically by a cloud point measurement, to a desired cloud point temperature with results of the comparison being utilized to control the flow rate of the side draw product stream so as to maintain the actual cloud point temperature of the side draw product stream substantially equal to the desired cloud point temperature. Use of the calculated cloud point temperature provides a means by which continuous control of the actual cloud point temperature of the side draw product stream can be maintained.

Abstract: In fractionating tower apparatus including a plurality of modules including multi-stage segments, the improvement comprising the combination of a plurality of vaporizers for heating feed liquid to different temperatures to vaporize fractions of correspondingly different volatilities, means for feeding the vaporized fractions to different multi-stage segments of the tower, means for withdrawing liquid sidestreams from a plurality of the segments, temperature control means for limiting the level of heavy components in at least one selected liquid sidestream withdrawn from a segment below a module in which vapor is flashed, and means for separately feeding reflux liquid from at least one segment to a segment below it.

Abstract: In a process in which liquid flows to a vessel and is then withdrawn from the vessel, method and apparatus is provided for implementing nonlinear liquid level control by providing a variable set point to a conventional level controller. The variable set point is a nonlinear function of the actual liquid level in the vessel. The variable set point enables the vessel to absorb disturbances in the flow rate of the liquid flowing to the vessel while the actual liquid level in the vessel remains between a desired high and low limit thus providing a smooth flow of liquid from the vessel.

Abstract: In a fractional distillation process in which a heating fluid and waste heat stream are utilized to supply heat to a fractional distillation column and in which the heat supplied from the waste heat stream is not controllable, control of the liquid level in the fractional distillation column is accomplished by manipulating the flow rate of the heating fluid so as to maintain a desired liquid level until such time as the flow rate of the heating fluid becomes zero at which time the flow rate of the external reflux to the fractional distillation column is manipulated to maintain a desired liquid level in the fractional distillation column. A switching of control of the liquid level provides a means by which an uncontrollable heat input may be provided to the fractional distillation column without losing control of the liquid level in the fractional distillation column.

Abstract: An alcohol still having a boiler with a valve for maintaining the amount of liquor constant. The boiler mounts a distilling column having a temperature controlled inlet for liquor to be distilled which assists in maintaining the operation at a constant optimum operating temperature.

Abstract: Control of multiple distillation columns for producing anhydrous alcohol suitable for blending with gasoline to produce gasohol. The distillation process involves production of a first-stage distillate containing a predetermined amount of water, followed by azeotropic distillation in the presence of a hydrocarbon entrainer to strip the distillate of its water content, leaving anhydrous alcohol as a bottom product. Tight controls are present during first-stage distillate production to hold its proof at an optimum value derived at through material balance calculations to minimize energy consumption for the overall system. Control over the dehydrating stage is accomplished by a combination of ratio control to regulate and maintain the proper proportion of the entrainer and temperature control to regulate within the column the actual inventory of entrainer.

Abstract: A control system for distillation column with a sidedraw line is provided wherein a prediction on the influence by changes in the feed stream with respect to the sidedraw composition is made.

Abstract: A contaminated solvent is first distilled in a distillation chamber (12) to drive off a substantial portion of the solvent which is condensed and recovered leaving a residual slurry (18) consisting of some solvent and the contaminants. A metering device (21) is cyclically operated to transfer precise amounts of slurry to a second distillation chamber where the slurry is deposited in an annular trough (26) formed in a heat plate (25). A spreader including a number of blades (27) moves the deposited slurry charge along the trough to an exit opening (44). The residual solvent in the slurry charge is vaporized, condensed and fed back into the first chamber (12). The remainder of the charge is exited through the trough opening (44) into a collection barrel (50) which is vented to pass back any solvent vapors to the second distillation chamber.

Abstract: A liquid containing a solvent to be evaporated is fed to a concentration chamber which is fluidly connected to an evaporation chamber maintained at a reduced pressure. A vapor compression means withdraws solvent vapor from the evaporation chamber, compresses the vapor and forces the compressed vapor to a liquification chamber. Regulator means responsive to the density of the liquid remaining within the concentration chamber will regulate the rate of solvent evaporation to provide a concentrate suitable for recycling.A method of operating the still of this invention utilizes the technique of increasing the compressor capacity until the compressor begins to surge and then reducing the capacity a fixed amount to provide the desired efficiency.

Abstract: The apparatus includes a housing enclosing a boiler in the lower portion and a water-filled condenser in the upper portion with an insulated partition between them. The entry of boiler feed water is controlled by a float valve in the boiler, and steam from the boiler is conveyed through the partition and thus through a condenser coil substantially immersed in the water in the condenser.

Abstract: A solar distillation unit is disclosed capable of operating entirely off solar radiation and intended for large scale industrial use offshore. A lens focusing system housed within an enclosed shell focuses the incident radiation from the sun on a heating element. Saltwater or contaminated fresh water is ejected toward the heating element at a predetermined rate resulting in the immediate evaporation of the water. The water vapor migrates and condenses on the cooler inner surface of the shell running to the bottom where it is collected and removed as fresh water.

Abstract: An electrically and/or solar heated distillation and fractionation system for separating ethanol-water mixtures comprised with an insulated inclined vaporization chamber divided into an upper solar absorbent vaporization section and a lower pre-heating section by a vaporization floor, float means to automatically control the ethanol-water feed to the lower portion of the preheating section when distillation is taking place, means to evenly distribute the ethanol-water mixture on the vaporization floor, means to heat the ethanol-water mixture in the distillation chamber, a packed fractionation column through which the vapors from the distillation chamber must pass, means to control the temperature at the top of the fractionation column-condensing means to recover and/or recycle distillate exiting to the upper portion of the distillation column and means to remove or recycle residual aqueous liquid from the lower end of the vaporization section.

Abstract: An apparatus for desalinating ocean waters by distillation and furnishing electrical power, utilizes an evaporator, barometric leg conduits, a closed condenser, ocean water circulating circuits for circulating warm surface water to the evaporator and cool ocean water to the condenser and using the mass flow of vapors evolved from the evaporator to drive a prime mover which in turn drives an electrical generator. A portion of the electrical power so-generated is used to control the operation of respective pumps and valves in the apparatus. The liquid level of the condensate water is controlled in a barometric leg condensate outlet conduit. The system is also provided with a vacuum pump at least for initiating a reduced pressure and particle separator channel means is provided to prevent liquid entrainment in the condenser.

Abstract: A dirty or otherwise contaminated volatile solvent or other treatment fluid including relatively more volatile non-flammable and relatively less volatile flammable constituents is recovered or reclaimed by boiling it off from its impurities. As the remainder is concentrated, the evaporated vapor becomes increasingly flammable. In a work process, a treatment tank is used for chemically treating work pieces in a volatile treatment fluid which has a liquid phase and a relatively non-flammable heavier-than-air vapor phase. In this process, heat energy is added to the fluid to maintain the upper vapor phase surface at a substantial distance above the upper liquid phase surface in the tank. When the treatment fluid becomes sufficiently contaminated with dirt introduced by the work pieces or otherwise, it must be removed from the tank and replaced with clean treatment fluid.

Abstract: A solar distillation unit is disclosed capable of operating entirely off solar radiation and intended for large scale industrial use offshore. A lens focusing system housed within an enclosed shell focuses the incident radiation from the sun on a heating element. Saltwater or contaminated fresh water is ejected toward the heating element at a predetermined rate resulting in the immediate evaporation of the water. The water vapor migrates and condenses on the cooler inner surface of the shell running to the bottom where it is collected and removed as fresh water.

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: A draw rate signal generator for an atmospheric crude distillation unit receiving crude oil and providing streams 1 through 5 and a reduced crude oil includes flow rate sensors sensing the flow rates of the crude oil and of streams 1 through 4 and providing corresponding signals. Analyzers sample the crude oil and provide signals corresponding to the 35% point temperature, the API gravity and the vapor pressure of the crude oil. End point analyzers sample streams Nos. 1 and 3 and provide signals representative of the end point temperatures of streams Nos. 1 and 3, respectively. 50% point analyzers sample streams 2, 3 and 4 and provide signals corresponding to the 50% point temperatures of streams Nos. 2, 3 and 4, respectively. A circuit connected to the sensors, to the crude analyzers, to the end point analyzers and to the 50% analyzers provide signals corresponding to the draw rates for streams Nos. 1 through 5 in accordance with signals from the sensors and analyzers.

Abstract: A vapor compression distillation apparatus and method are provided wherein scaling tendencies are eliminated. The raw feedwater has acid added to it in an amount sufficient to convert the carbonates and/or bicarbonates therein to carbon dioxide. The heated acidified feedwater is then deaerated to remove the carbon dioxide and other non-condensible gases. The deaerated water flows to the evaporator through a line having a valve therein controlled by the liquid level in the deaerator to maintain such level constant even though the tube side of the evaporator is being operated at a pressure less than that of the deaerator. This permits the evaporation to take place under a partial vacuum and at a boiling temperature of less than 212.degree. F. even though the deaerator is operated at atmospheric pressure. Vent steam from the evaporator is added to the deaerator to further preheat the feedwater, and as a sparging or stripping agent to aid in the elimination of carbon dioxide and other non-condensible gases.