WO2010126847A1 - Régulation thermodynamique d'une distillation à compression de vapeur - Google Patents

Régulation thermodynamique d'une distillation à compression de vapeur Download PDF

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Publication number
WO2010126847A1
WO2010126847A1 PCT/US2010/032462 US2010032462W WO2010126847A1 WO 2010126847 A1 WO2010126847 A1 WO 2010126847A1 US 2010032462 W US2010032462 W US 2010032462W WO 2010126847 A1 WO2010126847 A1 WO 2010126847A1
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WIPO (PCT)
Prior art keywords
evaporator
distillate
condenser
vapor
compressor
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PCT/US2010/032462
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English (en)
Inventor
Bruce D. Kaufman
Harry Nguyen
David C. Walther
Pamela Reily Contag
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Cobalt Technologies Inc.
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Application filed by Cobalt Technologies Inc. filed Critical Cobalt Technologies Inc.
Publication of WO2010126847A1 publication Critical patent/WO2010126847A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/28—Evaporating with vapour compression
    • B01D1/2887—The compressor is integrated in the evaporation apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/007—Energy recuperation; Heat pumps

Definitions

  • VCD vapor compression distillation
  • existing VCD devices are not equipped, either with hardware or software, to optimally separate variable or changing feed solutions such as might be expected in separating an acetone-butanol-ethanol (ABE) fermentation broth or other alcohol-water mixture.
  • ABE acetone-butanol-ethanol
  • existing VCD devices are built in a way to achieve specific thermodynamic conditions in an evaporator through a pressure monitor in the evaporator, but do not have the variability to alter this thermodynamic state depending on changing feed conditions.
  • VCD devices are designed with single speed compressors (which limit one's ability in achieving different thermodynamic states), cyclic flow control (which mimics more of a batch process than a continuous steady-state process), and a solid state relay control system not robust enough to handle variations in feed concentrations.
  • downstream hardware configurations for various VCD models (such as heat exchanger capacity), are designed to provide optimal performance for a single feed solution, but do not function as well under other feed solutions that may require larger flow rates, for instance.
  • the present invention provides a device comprising an evaporator section configured to contain a feed solution; a compressor fluidically connected to the evaporator section, wherein the compressor has a variable and controllable speed; a condenser section fluidically connected to the compressor and in thermal contact with the evaporator section; and a controller configured to control the speed of the compressor.
  • a device is provided that further comprises a sensor configured to sense the pressure or temperature of a vapor within the condenser section and communicate the pressure or temperature to the controller.
  • a device that further comprises a sensor configured to sense the pressure or temperature of a vapor within the evaporator section and communicate the pressure or temperature to the controller.
  • a device is provided that further comprises a a sensor configured to monitor the concentration of a solvent within the feed solution and communicate the concentration to the controller.
  • the invention may also provide a controller configured to control the speed of the compressor in response to the communication received.
  • a device is provided that further comprises a condenser section that is operable to form a distillate.
  • a device that further comprises a sensor configured to monitor the concentration of a distillate solution and communicate the concentration to the controller.
  • a device is provided that further comprises a secondary separator configured to accept the distillate from the condenser section to further separate and/or concentrate the distillate into a vapor component including a target product and a liquid component.
  • a device is provided that further comprises a sensor configured to monitor the flow rate of the target product and communicate the flow rate to the controller.
  • a device is provided that further comprises a heater in thermal contact with the evaporator section and a controller configured to control the strength of the heater.
  • a device that further comprises a heater in thermal contact with the condenser section and a controller configured to control the strength of the heater.
  • a device is provided that further comprises a heater in thermal contact with the secondary separator and a controller configured to control the strength of the heater.
  • the present invention provides a device comprising an evaporator configured to accept a mixture containing any number of components at any given ratio, optionally via a mixture feed apparatus; a condenser in thermal contact with the evaporator; a compressor configured to transfer a vapor from the evaporator to the condenser under increased pressure and temperature to produce a distillate and a residual solution; and a variable control element configured to control the thermodynamic conditions of the distillate.
  • variable control element of the device is at least one of the following: a variable speed compressor, a heater, or a mixture feed apparatus.
  • mixture feed apparatus of the device is a control valve or a variable speed pump.
  • a device is provided further comprising a programmable logic controller configured to control the variable control element.
  • a device further comprising at least one of: a sensor configured to sense the pressure of a vapor within the condenser and communicate it to the programmable logic controller; a sensor configured to sense the temperature of a vapor within the condenser and communicate it to the programmable logic controller; a sensor configured to sense the pressure of a vapor within the evaporator and communicate it to the programmable logic controller; a sensor configured to sense the temperature of a vapor within the evaporator and communicate it to the programmable logic controller; a sensor configured to monitor the concentration of a solvent within the mixture and communicate it to the programmable logic controller; a sensor configured to monitor the concentration of a solvent within the distillate and communicate it to the programmable logic controller; a sensor configured to monitor the concentration of a solvent within a secondarily separated distillate and communicate it to the programmable logic controller; or a sensor configured to monitor the flow rate of the mixture and communicate it to the programmable logic controller.
  • a device is provided further comprising a secondary separator configured to accept the distillate and separate the distillate into a liquid component and a vapor component including a target product.
  • a device is provided further comprising a sensor configured to monitor the flow rate of the target product and communicate it to the programmable logic controller.
  • a device is provided wherein the programmable logic controller controls the variable control element to regulate towards or maintain an increased mass flow rate of the target product in the vapor component.
  • a device wherein the programmable logic controller controls the variable control element to regulate towards or maintain a reduced energy use per mass flow rate of the target product in the vapor component. In another embodiment of this aspect of the invention a device is provided wherein the programmable logic controller controls the variable control element to regulate towards or maintain an increased mass flow rate of the residual solution. In another embodiment of this aspect of the invention a device is provided herein the programmable logic controller controls the variable control element to regulate towards or maintain an increased concentration of the residual solution
  • the present invention provides a method comprising a) performing distillation of a feed solution using a vapor compression distillation system that comprises an evaporator, a compressor and a condenser, wherein the evaporator and the condenser are in thermal communication with each other and the compressor transfers a vapor from the evaporator to the condenser under increased pressure and temperature to produce a distillate and a residual solution; and b) regulating the distillation to control the thermodynamic conditions of the distillate.
  • a vapor compression distillation system that comprises an evaporator, a compressor and a condenser, wherein the evaporator and the condenser are in thermal communication with each other and the compressor transfers a vapor from the evaporator to the condenser under increased pressure and temperature to produce a distillate and a residual solution; and b) regulating the distillation to control the thermodynamic conditions of the distillate.
  • thermodynamic conditions of the distillate regulates towards or maintains an increased mass flow rate of a target product in a solvent-containing vapor stream derived from the distillate.
  • controlling the thermodynamic conditions of the distillate regulates towards or maintains a reduced energy use per mass flow rate of a target product in a solvent containing vapor stream derived from the distillate.
  • controlling the thermodynamic conditions comprises controlling the condenser temperature and pressure.
  • a method wherein the method further comprises receiving sensor feedback from at least one of the following: a sensor configured to sense the pressure of a vapor within the condenser; a sensor configured to sense the temperature of a vapor within the condenser; a sensor configured to sense the pressure of a vapor within the evaporator; a sensor configured to sense the temperature of a vapor within the evaporator; a sensor configured to monitor the concentration of a solvent within the feed solution; a sensor configured to monitor the concentration of a distillate stream; a sensor configured to monitor the concentration of residual solution exiting the evaporator section; a sensor configured to monitor the flow rate of the feed solution; a sensor configured to monitor the temperature of a secondary separator, a sensor configured to monitor the temperature of a secondary separator or a sensor configured to monitor the flow rate of a target product in a solvent-containing vapor stream derived from the distillate.
  • a method wherein regulating the distillation to control the thermodynamic conditions of the distillate comprises: performing a logical function incorporating sensor feedback; controlling the speed of the compressor; controlling the strength of a heater in thermal communication with the evaporator, and/or condenser sections; and controlling the thermodynamic conditions of a secondary separation section.
  • a method is provided wherein wherein the feed solution is an aqueous solution and the target product is an alcohol.
  • a method is provided wherein the feed solution is an ABE fermentation broth and the target product is butanol.
  • Fig. 1 shows an example of a vapor compression distillation device.
  • Fig. 2 shows an example of plate type heat exchangers which form alternating evaporating and condensing chambers of an evaporator/condenser (E/C) core.
  • E/C evaporator/condenser
  • Fig. 3 shows a nested shell and tube arrangement.
  • Fig. 4 shows an interspersed shell and tube arrangement.
  • Fig. 5 shows an example of a vapor compression distillation device along with energy transfer and mass flow.
  • Fig. 6 shows an implementation of a control strategy.
  • Fig. 7 shows an implementation of an operator interface for a vapor compression distillation apparatus.
  • Fig. 8 shows an additional embodiment of the invention, including various control relationships.
  • Fig. 9 shows the results of a distillation of butanol from a feed solution by thermodynamic control.
  • Fig. 1 shows an example of a VCD device.
  • a VCD unit 100 produces a distillate and a residual solution from an incoming solution.
  • An incoming solution enters as a feed in through an inlet 101.
  • a VCD unit evaporates the incoming solution, compresses the overhead vapor and sends the vapor to a condenser 104, where some of the vapor is condensed. Some of the incoming solution remains in an evaporator 102 to form a residual solution. A residual solution is removed from the evaporator 102 through an outlet for waste 106. The condensed vapor in the condenser 104 forms a distillate. The distillate is removed from the condenser 104 through an outlet for the distillate 105.
  • An incoming solution may be a mixture containing a target product.
  • a distillate has a higher concentration of the target product than the incoming solution.
  • the residual solution may have a higher concentration of the target product.
  • the incoming solution is an Acetone Butanol Ethanol (ABE) fermentation broth.
  • the incoming solution is waste water, brackish water, salt water, sea water, or non-potable water.
  • the target product is acetone, butanol, ethanol, methanol, propanol, a biofuel, potable water, or a combination thereof.
  • the vapor in the evaporator 102 has a vapor pressure and temperature.
  • the vapor in the condenser 104 has a vapor pressure and temperature.
  • the energy of condensation is transferred back to the evaporator 102, thereby reducing the amount of heating energy that is required to boil and evaporate a solution.
  • the energy transferred may be latent heat. Heat energy is transferred from a condenser 104 of a VCD unit back to an evaporator 102 of the VCD unit in various ways.
  • a VCD unit may be configured in any way to allow heat transfer between a condenser and evaporator.
  • the process contains plate type, energy efficient, heat exchangers, which act as heat transfer plates to provide energy from a condenser to an evaporator. See generally U.S. Patent No. 4,978,429 and U.S. Patent No. 5,968,321.
  • plate members 201 are arranged so that they form alternating evaporating and condensing chambers 202, 203, as shown in Fig. 2.
  • the evaporating chambers 202 are connected by a manifold that collects the residual solution.
  • the condensing chambers 203 are connected by a manifold that collects the distillate. From these chambers, the residual solution, distillate, and/or vapor is removed from an evaporator/condenser (E/C) core of a VCD unit. In some cases, the entire process is enclosed in an insulated shell to reduce heat loss to the environment.
  • E/C evaporator/condenser
  • any other type of distillation unit known in the art to produce a distillate and a residual solution from an incoming solution may be used.
  • shell and tube heat exchangers may also be employed, where one or more tube is disposed inside a shell, and different fluids may flow within the tube and within the shell outside the tube.
  • two multistage configurations can be envisioned to effectively couple excess enthalpy for the energy efficient distillation of a multiple component liquid as shown schematically in the attached figures.
  • one configuration consists of a nested set of tubes , 302 within a shell 303.
  • Fig. 4 consists of an interspersed tube arrangement 401 within a shell 402.
  • Vapor compressors not shown in the figures would collect evaporated materials from manifolds and would supply compressed vapors to additional manifolds.
  • a VCD unit can be utilized in either batch or continuous distillation processes.
  • the heat exchange between an evaporator and condenser of a VCD unit provides an indirect but highly coupled means of altering the thermodynamic conditions within these chambers. This coupled system can become unstable if alternate control measures are not integrated.
  • variable speed compressor provides a variable pressure differential based on the compressor operation speed.
  • Vapor compression distillation devices have traditionally used single speed compressors since they've been designed to operate on a constant feed solution, which requires little to no variation in compression ratios for optimal conditions to be achieved.
  • the speed of the compressor is controllable, which enables control of the pressure differential across the compressor. Controlling a compressor may vary the compressor speed, which may vary the pressure differential.
  • a compressor motor may be powered by a variable frequency drive (VFD), which enables the compressor speed, and therefore the pressure differential, to be varied.
  • VFD variable frequency drive
  • the compressor is fluidically connected to the evaporator and the condenser.
  • thermodynamic conditions for the condenser for a given set of thermodynamic conditions in the evaporator.
  • a compressor will provide a direct impact on both the amount of separation possible by the VCD as well as the amount of energy recycled back to the evaporator.
  • the coupling between the evaporator and condenser can affect the choice of process setpoint.
  • other factors can affect the transfer of heat between the condenser and evaporator.
  • a desirable trait for a VCD system is long term operation at optimal conditions despite process variations due to changes in heat transfer. It is desired to maintain optimal operating conditions to account for the changing levels of heat transfer, which occur with characteristic times on the order of hundreds of hours. It is also desired to maintain optimal operating conditions when heat transfer changes occur at other orders of time, such as hours, days, or months.
  • the variable speed compressor is a centrifugal compressor.
  • Other compressors known in the art such as axial, piston, thermocompression, or any other type of compressor can be used as well.
  • a centrifugal compressor is not capable of achieving desired pressure differentials, because of flow stall or surge, another compressor may be used.
  • a backup compressor is provided, so that if a primary compressor is unable to achieve a desired pressure differential, the backup compressor can help achieve or get closer to the desired pressure differential.
  • Another control measure for altering the thermodynamic conditions within a VCD unit is a heater to add heat to an evaporating mixture within an evaporator.
  • the heater can be an electric heater, or any other type of heater capable of providing heat to the evaporator.
  • a heater can be used to provide heat to condenser.
  • One or more heaters can be used to provide heat to the various parts of a VCD unit.
  • the amount of heat provided by a heater is controlled by controlling the amount of time that a heater is turned on. For instance, a heater is turned on and off periodically to provide the desired amount of heat. In some other cases, the magnitude of heat provided by a heater when the heater is on is controlled.
  • FIG. 5 shows an example of a VCD device 500 along with energy transfer and flow.
  • the VCD device includes an inlet 501 for feed in, which allows a mixture to enter an evaporator section 502.
  • the mixture can contain any number of components at any given ratio.
  • the mixture comprises alcohol and water.
  • the mixture includes an acetone -butanol-ethanol (ABE) fermentation broth, or a mixture that includes acetone, butanol, ethanol, and/or water at some stage of distilling an ABE fermentation broth.
  • the feed mixture can contain a target product.
  • the target product is an alcohol
  • a mixture is an aqueous solution with alcohol and one or more other components.
  • a target product is butanol and the mixture is an ABE fermentation broth.
  • Fermentation broths can be produced by all manner of microorganisms including bacteria and fungi.
  • the term "fermentation broth” includes broths with products produced fermentatively, metabolically, and synthetically, i.e., a genetically engineered synthetic pathway.
  • Bacteria covered by this invention include Gram-negative and Gram-positive bacteria.
  • Non-limiting examples of Gram-positive bacteria include bacteria found in the genera of Staphylococcus, Streptococcus, Bacillus, Mycobacterium, Enterococcus, Lactobacillus, Leuconostoc, Pediococcus, and Propionibacterium.
  • Gram-negative bacteria include bacteria found in the genera Pseudomonas, Zymomonas, Spirochaeta, Methylo sinus, Pantoea, Acetobacter, Gluconobacter, Escherichia and Erwinia.
  • the bacteria are strict or obligate anaerobes such as Clostridium, e.g., C. acetobutylicum, Butyrivibrio fibrosolvens and Clostridium species such as C pasteruianum.
  • the microorganisms are aerotolerant and are capable of surviving in the presence of small concentrations of oxygen. In some cases, the microorganisms are aerotolerant due to the presence of one or more heterlogous and/or recombinant nucleotides.
  • the microorganisms are fungi and the fungi are yeasts.
  • yeasts include, but are not limited to, Saccharomyces cerevisiae, S. bayanus, S. carlsbergensis, S. Monacensis, S. Pastorianus, and S. uvarum.
  • Other examples of anaerobic or aerotolerant fungi include, but are not limited to, the genera Neocallimastix, Caecomyces, Piromyces and other rumen derived anaerobic fungi.
  • An evaporator section 502 is configured to accept and evaporate the mixture, such that an overhead vapor and residual solution are separated.
  • the residual solution is removed from the evaporator through an outlet for waste 506.
  • the residual solution comprises impurities extracted from the incoming mixture to form a waste stream.
  • the waste stream can be in the form of a thickened sludge.
  • the waste stream can also mostly comprise water.
  • the residual solution passes to an inlet heat exchanger (to be discussed in greater detail below) where its heat is used to help pre-heat the incoming mixture.
  • the residual solution can pass out of the system to a holding tank for further processing, recycling, storage, or disposal.
  • a variable speed compressor 503 compresses the overhead vapor and sends the vapor to a condenser section 504, where some of the vapor is condensed.
  • the condensed vapor and uncondensed vapor in the condenser section forms a distillate, which is removed from the condenser section 504.
  • the distillate can be removed through an outlet for the distillate 505.
  • the evaporator and condenser sections are in thermal communication with one another, such that latent heat is transferred from the condenser section to the evaporator section.
  • a VCD device also includes a controller that controls the speed of the compressor 503, and thereby controls the pressure differential between the condenser section 504 and the evaporator section 502.
  • a VCD device 500 can also include one or more heaters 507 that provide heat to one or more parts of the VCD device.
  • heaters 507 provide heat to the evaporator section 502.
  • the amount of heat provided by the heaters can also be controlled by a controller.
  • the controller may be configured to control any variable control element associated with the VCD device, including, but not limited to the variable speed compressor 503, the heater 507, or a mixture feed apparatus.
  • One method of controlling the thermodynamic conditions within a condenser stage 504 of a VCD unit, and thereby controlling the thermodynamic conditions of the distillate formed in the condenser stage 504, includes regulating the distillation of the VCD unit.
  • the distillation of a VCD unit may be regulated in any number of ways, including controlling a variable control element, feed rate or composition, VCD unit configuration, or any other ways known in the art for regulating distillation.
  • the distillation of a VCD unit is regulated by controlling a variable speed compressor 503 to maintain or regulate towards optimal operating conditions, and by controlling the heater 507 to provide fine tuning of process control.
  • Using the compressor 503 as a primary control is a more efficient method of changing thermodynamic conditions than using a heater 507 as a primary control. Efficiency can be measured by the minimization of the combined energy of the compressor and heater normalized by the amount of mixture processed. In other words, greater efficiency is provided when the combined energy input to the variable control elements are minimized per amount of mixture process.
  • a heater is used as a primary control.
  • other variable control elements are used as a primary control.
  • Optimal setpoints for compressors, heaters, and/or other variable control elements can be determined for desirable thermodynamic conditions.
  • the desirable thermodynamic conditions may be specified for a condenser, and setpoints can be determined accordingly.
  • the desirable thermodynamic conditions may be specified for an evaporator or any other VCD component, and setpoints can be determined accordingly.
  • Such desirable thermodynamic conditions may be determined to reach an optimization goal.
  • one optimization goal may be to reduce energy use for the VCD device per mass flow rate of a target product.
  • one or more desirable thermodynamic conditions may exist for the VCD unit.
  • a specific pressure and temperature within a condenser may yield a reduced energy use per mass flow rate of a target product.
  • one or more combinations of pressure and temperature within a condenser or evaporator may yield a desired result.
  • a user defines desired thermodynamic conditions at a user defined interface, and setpoints are determined accordingly. In other embodiments, the user defines the setpoints directly.
  • a user may define an optimization goal, an incoming solution composition, a VCD unit configuration, or any other parameter, and set points or control schemes can be determined accordingly.
  • Controlling a variable speed compressor enables the pressure inside the condenser stage to be set, which indirectly affects the temperature within the condenser stage.
  • additional heating elements can provide additional heat to an evaporator stage besides the latent heat that is transferred from the condenser, which affects the temperature within the condenser stage.
  • a combination of compressor and heating element control is sufficient to achieve desired thermodynamic conditions within the condenser stage.
  • thermodynamic conditions of the VCD device Another variable that can affect thermodynamic conditions of the VCD device is feed rate of an incoming solution.
  • the flow rate of the solution affects the thermodynamic conditions within the evaporator by affecting factors such as evaporator temperature, pressure, or rate of vaporization.
  • the flow rate of the solution can also affect the control stability of the system.
  • An approach to maintain control stability and some energy efficiency is to maintain steady conditions within the VCD device. For instance, the flow of solution into and through the device could remain constant to provide steady conditions.
  • VCD devices do not operate under steady flow conditions, but rather under conditions of flow oscillation determined by slow draining and rapid refilling of solution in the evaporator. In such a situation, steady conditions can be maintained or regulated towards by maintaining a constant or near-constant level of mixture within the evaporator.
  • a sensor is installed in conjunction with a control valve for the feed solution.
  • the sensor can be an analog level sensor, or any other type of sensor to detect the level of mixture within an evaporator, or whether the mixture level is within a desired range.
  • the control valve can be a proportional control valve or any other type of valve that can control the amount of incoming solution.
  • a proportional control valve modulates from 0% to 100% based on the liquid level within the evaporator. Valve position is inversely proportional to the liquid level, such that if the liquid level is high, the valve narrows its opening, and if the liquid level is low, the valve widens its opening.
  • a mixture feed apparatus can utilize other flow rate controls, such as a variable speed pump. Another way of controlling flow rate is by using a discrete on/off control for relatively short periods of time to provide feed solution when the liquid level is low.
  • the composition and/or concentration of the incoming feed solution can also affect the thermodynamic control of the VCD device.
  • the composition of the incoming feed solution remains more or less constant.
  • the composition of the incoming feed solution can be predetermined so that the control for the VCD device can accommodate the predetermined solution.
  • the composition may be user-defined, as indicated through a user interface, and desired thermodynamic conditions are determined accordingly.
  • sensors are provided that determine one or more physical parameters of the incoming feed solution and the desired thermodynamic controls of the system are adjusted accordingly.
  • sensors may include infrared spectroscopy analytical equipment, such as Fourier transform infrared spectroscopy (FTIR), or any other analytical equipment that determines concentration, for real-time monitoring of component composition and concentration.
  • FTIR Fourier transform infrared spectroscopy
  • the thermodynamic conditions of the VCD device (such as the thermodynamic conditions within the condenser) are measured and compared to analytical equipment data about the condensed product concentration in real-time, and the compressor and heater are automatically adjusted to achieve this state.
  • an incoming feed solution passes through a heat exchanger and a degassing column.
  • the distillate is passed through a secondary separator 508, where separation between a vapor and liquid take place.
  • the secondary separator is a degassing column.
  • the secondary separator includes a secondary heat exchanger.
  • the secondary heat exchanger can be used for fine turning thermodynamic conditions of the distillate.
  • the heat exchanger can add or remove heat to the distillate of the secondary separator.
  • the vapor component 509 of the distillate has a higher concentration a target product than the liquid component 510.
  • a target product is alcohol and a greater concentration of alcohol is found in the vapor component 509.
  • the liquid component 510 may comprise mostly water. The vapor can then be passed to a chiller, where it is condensed and exits the chiller as a liquid target product.
  • a target product may be any desired product.
  • a target product is an alcohol.
  • a target product is a specific type of alcohol, such as butanol, acetone, or ethanol.
  • a target product can be water, any solvent, or any component of a mixture.
  • the chiller is an inlet degassing column, where the product receives some cooling from the incoming feed solution.
  • the chiller is an inlet heat exchanger, where the product receives some cooling from the incoming feed solution.
  • the vapor can be cooled by any combination of a degasser or heat exchanger.
  • the liquid component from the secondary separator passes to the inlet heat exchanger and provides heat to help pre-heat the incoming solution. The liquid component may then pass out of the system to a holding tank for further processing, recycling, storage, or disposal.
  • the liquid component has a higher concentration of a target product than a vapor component.
  • the vapor and/or liquid component passes to an inlet degasser and/or heat exchanger to be cooled and/or provide heat to an incoming solution.
  • the liquid component can exit as the target product and the condensed vapor can exit to a holding tank for further processing, recycling, storage, or disposal.
  • the distillate does not pass through a secondary separator and the target product is the distillate.
  • the target product passes to an inlet degasser and/or heat exchanger to be cooled and/or provide heat to an incoming solution.
  • VCD control including, but not limited to compression, heat, or flow
  • VCD control including, but not limited to compression, heat, or flow
  • Specific thermodynamic conditions to achieve desired operation are determined by feed solution composition/concentration and desired products.
  • An original setpoint is determined by an understanding of the conditions and concentration of the incoming feed solution, and the thermodynamic conditions desired to achieve a desired and efficient separation.
  • the incoming feed composition/concentration can be predetermined or predefined by a user, or can be determined through a sensing apparatus.
  • sensors are provided to measure characteristics of a VCD unit and provide feedback to a controller.
  • sensors are as follows: a condenser pressure sensor, a condenser temperature sensor, an evaporator pressure sensor, an evaporator temperature sensor, a pressure sensor for a secondary separator, or a temperature sensor for a secondary separator.
  • Additional examples sensors include a sensor configured to monitor the concentration of a solvent within a feed solution, a sensor configured to monitor the concentration of a distillate, a sensor configured to monitor the concentration of a residual solution, a sensor configured to the monitor the concentration of a secondarily separated distillate, a flow rate sensor for a feed solution, or a flow rate sensor for a target product.
  • a distillate may be secondarily separated to yield a vapor component and a liquid component.
  • the vapor component may be condensed to liquid form.
  • Monitoring the flow rate or concentration of a target product can include monitoring the flow rate of the condensed liquid form, the flow rate of the liquid component, or the flow rate of the distillate.
  • Another example of a sensor is a sensor to monitor the liquid level within an evaporator, or a liquid level within a secondary separator.
  • temperature sensors are: thermometers, thermocouples, temperature sensitive resistors (thermistors and resistance temperature detectors), bi-metal thermometers, or thermostats.
  • Examples of pressure sensors are altimeters, barometers, barographs, pressure gauges, or variometers.
  • sensors to monitor flow rate are flow sensors (such as potentiometers or microsensors), anemometers, flow meters, gas meters, water meters, or mass flow sensors.
  • sensors to monitor concentration or compositions are sensors utilizing infrared spectroscopy, such as FTIR.
  • sensors to monitor liquid levels are analog level sensors such as capacitance sensors for example.
  • the control system is designed to operate the VCD system safely and to optimize the distillation process.
  • optimization is defined as maximizing energy efficiency.
  • optimization can be to regulate towards or maintain a reduced energy use per mass flow rate of a target product.
  • optimization can be to regulate towards or maintain an increase mass flow rate of the target product.
  • Optimization can be regulating towards or maintaining any user-defined goal including, but not limited to, achieving a desired target product concentration, maximizing target product concentration, achieving a desired target product composition, achieving a desired target product flow rate, minimizing system energy use, or minimizing a mass flow rate of residual solution.
  • One aspect of the invention provides determining an optimization definition and a corresponding set of thermodynamic conditions to maintain or regulate towards an optimization definition.
  • an optimization definition is set. As mentioned previously, optimization can be set as regulating towards or maintaining a reduced energy use per mass flow rate of a target product. In other embodiments, an optimization definition is determined by a user. A user may select from a set of possible optimization definitions.
  • there may be one or more set of desirable thermodynamic conditions. For instance, there is a specific temperature and pressure within a condenser that results in regulating towards or maintaining a reduced energy use per mass flow rate of a target product. There can be one or more combinations of temperatures and pressures or other thermodynamic conditions within a condenser or evaporator that can result in achieving a user goal.
  • Varying variable control elements moves a system toward desired thermodynamic conditions. For instance, varying a compressor speed affects a pressure difference within an evaporator and condenser. Varying a heater affects a temperature of a condenser and/or evaporator.
  • the variable control elements can be varied separately or in combination to yield thermodynamic conditions for the system. For instance, only a compressor speed may be varied, only a heater may be controlled, only a mixture feed apparatus may be controlled, or any combination of the control elements can be controlled.
  • varying thermodynamic conditions in the condenser or evaporator can affect the thermodynamic conditions of the other components.
  • Controls of a control system may be discussed in sub-parts below for separation control, infeed control, cooling water control, and start-stop sequences.
  • Fig. 6 shows an example of an implementation of a control strategy in accordance with one embodiment of the invention.
  • a separation control controls the thermodynamic conditions of an E/C core condenser.
  • a separation control may do this by controlling both the temperature and pressure of the condenser (TE COND and PT COND respectively).
  • the temperature and pressure can be measured by a thermocouple 601 and pressure transducer 602 respectively.
  • the separation of a solution, such as alcohol and water separation, occurs most efficiently at a specific temperature and pressure of a condenser.
  • the condenser temperature TE COND is controlled by at least one of the following two variables: compressor discharge pressure ("CDP") for a compressor 603 and core heaters 604.
  • CDP can be used as a primary control and source of heat for achieving the desired TE COND where greater CDP leads to greater TE COND -
  • An additional fine tuning control can be provided by another source of heat, namely the core heaters 604.
  • a separation control controls the thermodynamic conditions of an E/C core evaporator.
  • a separation control may do this by controlling both the temperature and pressure of the evaporator (TE EVAP and PT EVAP respectively).
  • the temperature and pressure can be measured by a thermocouple 615 and pressure transducer 616 respectively.
  • the separation of a solution, such as alcohol and water separation, occurs most efficiently at a specific temperature and pressure of an evaporator.
  • CDP is a computed value, equal to the difference between condenser and evaporator pressures (PT COND - PT EVAP )-
  • the value of the CDP depends primarily on the compressor speed, where higher speed equals higher CDP.
  • CDP can also be affected by inlet and discharge pressures and temperatures, solution properties, and the mechanical design of the compressor (such as impeller design).
  • the compressor motor 605 is powered by a VFD 617.
  • the control system has the ability to vary the compressor speed and thereby control the CDP.
  • a controller can communicate with a current transducer 618 for the compressor to regulate motor speed.
  • a proportional-integral-derivative (PID) control algorithm is used for CDP control.
  • PID proportional-integral-derivative
  • other control algorithms as known in the art, such as PI controls, PD controls, proportional controls, integral controls, derivative controls, model predictive controls, or cascade controls are used.
  • a setpoint for a CDP is determined. A user can specify the setpoint, or the setpoint may be determined in response to preprogrammed instructions for various conditions. The control system attempts to maintain the specified CDP.
  • a setpoint may be the pressure of the condenser PT COND -
  • Discharge flow rate from the E/C core is defined as the flow rate of the distillate, which in some cases is defined as the sum of the flow rate of the liquid 608 and vapor 607 components (FT CONDENSATE + FT PROD )-
  • the flow rate can be measured by a flow transducer 606, 607. If the discharge flow rate is showing a low flow while the compressor 603 is running in a normal operation mode, and the pressure within the evaporator PT EVAP is greater than atmospheric pressure, an alarm is provided that the compressor is operating at too low of a speed.
  • the system can respond by shutting down the motor and heaters.
  • a user can receive a "compressor speed too low” alarm.
  • a setpoint is too high, such that a compressor 603 can not operate at a speed high enough to achieve the setpoint, the compressor simply runs at full speed. An alarm is provided of this condition.
  • a user of the system may receive a "compressor discharge deviation" alarm.
  • heaters 604 are controlled with a discrete (on/off) output to heater relay YV HTR 608.
  • a heater can be controlled by a relay for power control and a current transducer. Heat added by these electrical heaters acts as a trim to add whatever additional heat is needed, beyond what the CDP can achieve, to achieve the desired condenser temperature TE COND -
  • a PID control algorithm is used to control TE COND using the heater relay YV HTR 608.
  • a typical PID loop delivers an output (calculated result) as a continuous value from 0 to 100 percent.
  • Software is used to convert this 0-100 value to a time interval; the heater is pulsed on and off according to the time interval to approximate a continuous heating output.
  • a continuous heating element is used, and a software is used to convert the 0-100 value to a heater output setting.
  • the heater 604 simply operates at maximum power, or maximum on setting. An alarm is provided of this condition.
  • a user of a system may receive a "condenser discharge temperature deviation" alarm.
  • An infeed control controls the flow of a feed solution into an E/C core. Start and stop sequences to be discussed in greater detail below provide more detail on how infeed is controlled.
  • the infeed is controlled via a mixture feed apparatus.
  • a flow transducer 614 can monitor the flow rate of the infeed.
  • a control valve 610 modulates between 0 and 100 percent to vary the amount of feed.
  • the control valve modulation depends on the liquid level in the evaporator LT EVAP , which may be sensed by a level transducer 609. Valve position is controlled to be inversely proportional to the liquid level, such that if the liquid level is high, the valve narrows its opening, and if the liquid level is low, the valve widens its opening.
  • a mixture feed apparatus can utilize other flow rate controls, such as a variable speed pump.
  • Another way of controlling flow rate is by using a discrete on/off control for relatively short periods of time to provide feed solution when the liquid level is low.
  • the infeed control is used to regulate toward or maintain keeping a liquid level inside the evaporator at a constant, user defined value.
  • a cooling water control regulates the compressor temperature.
  • a cooling water loop (“Aquaseal") can be used to cool a compressor. Any sort of apparatus can be used to control the cooling water flow, including but not limited to, a continuous control valve or a control feature that either allows or does not allow flow to occur.
  • a control apparatus may allow the cooling water to flow or not allow the cooling water to flow in an on/off arrangement. For example, cooling water may flow as long as a VCD unit is not off.
  • the amount or flow rate of cooling water can be controlled along a continuous spectrum. For example, more cooling water may flow when compressor temperature is detected to be high.
  • the cooling water control may be controlled as described in start and stop sequences to be discussed in greater detail below.
  • Start and stop sequences for a VCD unit provide steps that occur throughout the course of VCD operation.
  • Various controls are implemented at each of the steps.
  • steps for a VCD unit may include: (1) the VCD unit is off, (2) the VCD unit is warming up, (3) the VCD is engaged in normal operation, (4) the VCD is in post-run flush, and (5) the VCD is cooling down.
  • a VCD operator presses a start button on an operator interface to start the VCD.
  • the operator interface can be any sort of human computer interface, such as a Wonderware Intouch 10.0 on a PC or any form of software on a PC or any sort of operator interface that enables a user to interact with a VCD unit.
  • the operation of a VCD unit may be initiated remotely and/or automatically. For example, a VCD unit may be scheduled to start operation at a particular time of day.
  • a heater may be operating at full capacity while a compressor may be operating at a preset value.
  • the infeed and cooling water are on.
  • the warmup step takes place while the evaporator of the E/C core is heated to a boiling point.
  • the warmup step continues until a temperature setpoint, such as TE COND , is attained.
  • the warmup process can take several hours, or can take any amount of period to heat the evaporator to a boiling point, whether that time be on the order of seconds, minutes, hours, or days.
  • the CDP and heater PID loops automatically switch to a manual (fixed output) mode.
  • the compressor In the manual mode, during the warmup, the compressor is set at some speed, such as the allowable minimum.
  • An operator may enter a value for a preset value for the compressor, such that a value of 0 can be entered if the compressor is intended to be idle during this step. The operator can enter the value by interacting with an operator interface.
  • a heater can run at 100 percent during a warm-up step.
  • the VCD unit enters the third step of normal operation after the warm-up temperature (applied to TE COND ) has been reached.
  • a heater may be operated to control TE COND
  • a compressor may be operated to control CDP.
  • the infeed and cooling water are on.
  • PID loops automatically switch to automatic and the desired setpoint controlled for.
  • various control steps can be used, including but not limited to: controlling a compressor as a primary control and a heater as fine-tuning, controlling a compressor alone, controlling a heater alone, controlling infeed, or controlling any other variable control element that affects operation of a VCD unit.
  • VCD unit While a VCD unit is operating, a VCD operator can stop operation via a button on an operator interface, or through any other means known in the art. In some embodiments, the end of the operation is controlled remotely or automatically. A VCD unit can automatically shut down at a specified time each day, when a particular condition is fulfilled, or when the system detects a malfunction or cause for alarm.
  • a fourth step of VCD operation is initialized when the signal to stop the sequence is detected.
  • a heater can be on at a preset value and a compressor can be on at a preset value. Infeed and cooling water are also on.
  • the fourth step flushes the VCD with water through the solution inlet port.
  • the flushing solution can be any cleansing solution or mixture.
  • a series of solutions is introduced to the VCD unit to flush the unit.
  • the flush can be set to operate for a specified period of time, or when a certain condition is detected.
  • an operator has the ability to enter Xtime, where X time is the duration of the flush.
  • the operator can also enter heater and compressor preset values on an operator interface.
  • This post-run flush step can be manually activated when needed.
  • a fifth step of VCD operation is initialized when the post-run flush is over, when a hardwired emergency stop button is pressed, or when an alarm is activated.
  • the heater, compressor and infeed are stopped.
  • the cooling water remains on. If the X time for post-run flush is set to zero, the sequence automatically proceeds to the cool down step once the normal operation step is stopped.
  • the cooldown step continues until a preset cooldown temperature TE AQA0 is reached.
  • the cooldown setpoint is reached, the cooling water is shut off and the sequence returns to the off step.
  • the cooldown step continues for a specified period of time. The cooldown step can continue until any other desired condition is detected. Such setpoints or desired conditions can be set by a user through an operator interface. The end of the cooldown step can also be signaled through manual intervention.
  • a VCD system can include a programmable logic controller (PLC) that interacts with the operation of the VCD unit.
  • PLC programmable logic controller
  • the PLC monitors and controls the VCD unit.
  • a PLC can be an Allen-Bradley 1769-L32E CompactLogix, or any other computer system.
  • the PLC performs and reports the effectiveness calculation of any heat exchanger within the VCD system based on factors, such as inlet and outlet temperatures and mass flow rates of feed solution, waste, condensate, or product, depending on the heat exchanger setup.
  • heat exchangers are commonly used prior to the EC core to heat the incoming feed solution with condensate from the EC core.
  • the effectiveness of the heat exchanger is calculated based on the following formula:
  • Effectiveness Cc ⁇ NDENSATE [(TElc ⁇ NDENSATE )-(TE2 CONDENSATE )]/C mm [(TElc ⁇ NDENSATE )-(TEl FEED )]
  • heat capacity rate C CONDENSATE is a product of condensate mass flow rate in kg/s and specific heat coefficient in J/kgK
  • C mm is a smaller value of C CONDENSATE and C FEED -
  • an operator is able to override controls and variable control elements. For instance, an operator is able to override control valves or switches, heaters, or control motors. An operator may override the various elements in a maintenance mode.
  • an operator interface can be provided that enables operator interaction with the system.
  • the operator interface includes controls, such as start, stop and setpoint adjustment.
  • the operator interface also includes status displays and alarms or alerts.
  • the operator interface includes security features, such as password protection. In other embodiments, there is no password protection.
  • An operator interface can require confirmation before implementing a system change. For example, an operator interface includes "Are you sure?" prompts for start and stop commands to avoid accidental start or stop. An example of an operator interface is shown in Figure 7.
  • Various sensors and apparatus can be in place to detect and handle failures.
  • a normally open valve is installed in parallel with a control valve for a cooling loop to allow Aquaseal (or other coolant) supply to a bearing case in the event of a power failure.
  • backup battery or generator systems can be implemented in the event of a power failure to ensure that a VCD unit is able to continue to operate or to wind down accordingly.
  • a detector can be installed to detect an alcohol leak or hazardous gas leak and to trigger an alarm to shut down the machine.
  • alarms and warnings can be provided in the system.
  • One embodiment of such an alarm and warning system is provided as follows.
  • the alarms and warnings are presented on an operator interface, which is configured to present the alarm or warning to an operator.
  • An alarm or warning can be visual and/or auditory.
  • Alarms require operator acknowledgement to clear. For instance, when a sensor detects that a compressor speed is too low, the an alarm is presented and does not clear until an operator provides some acknowledgement or confirmation, even if the compressor speed later falls into an acceptable range. Warnings clear automatically when a measured variable is back within limits. For instance, while a temperature is too low, a warning can be presented while the temperature is outside the desired range, but once the temperature falls back within the desired range, the warning is cleared.
  • a VCD does not start a sequence if there are any active alarms or warnings, and does not automatically restart. An operator has to clear the alarm or warning and then restart the VCD. In some cases, a VCD continues in the present mode of operation, depending on the alarm or warning. In some cases, an alarm or warning causes a VCD to shut down, or initiate a shut-down process.
  • alarms or warnings that may be provided by the system are not limited to the examples provided herein.
  • a compressor temperature high warning is active in warmup and normal operation steps, and occurs when a compressor temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a compressor temperature too high alarm is active in warmup and normal operation steps, and occurs when a compressor temperature is higher than an even higher alarm setpoint that is higher than the high alarm setpoint for the compressor temperature high warning.
  • a compressor temperature too high alarm can also occur when ITS (compressor backing plate thermal switch) is closed.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor temperature thermocouple detective alarm is active in normal operation, and occurs when a compressor temperature is measured to be less than a low temperature setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor bearing case temperature high warning is active in warmup and normal operation steps, and occurs when a compressor bearing case temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a compressor bearing case temperature too high alarm is active in warmup and normal operation steps, and occurs when a compressor bearing case temperature is higher than an even higher alarm setpoint that is higher than the high alarm setpoint for the compressor bearing case temperature high warning.
  • a compressor bearing case temperature too high alarm can also occur when 2TS (compressor bearing case thermal switch) is open.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor bearing case thermocouple detective alarm is active in normal operation, and occurs when a compressor bearing case temperature is measured to be less than a low temperature setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor motor temperature high warning is active in warmup and normal operation steps, and occurs when a compressor motor temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a compressor motor temperature too high alarm is active in warmup and normal operation steps, and occurs when a compressor motor temperature is higher than an even higher alarm setpoint that is higher than the high alarm setpoint for the compressor motor temperature high warning.
  • a compressor motor temperature too high alarm can also occur when 3TS (motor thermal switch) is open.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor motor thermocouple detective alarm is active in normal operation, and occurs when a compressor motor temperature is measured to be less than a low temperature setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a heater temperature high warning is active in warmup and normal operation steps, and occurs when a heater temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a heater temperature too high alarm is active in warmup and normal operation steps, and occurs when a heater temperature is higher than an even higher alarm setpoint that is higher than the high alarm setpoint for the heater temperature high warning.
  • a heater temperature too high alarm can also occur when 4TS (heaters thermal switch) is open.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a heater temperature thermocouple detective alarm is active in normal operation, and occurs when a heater temperature is measured to be less than a low temperature setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • An evaporator liquid level low warning is active in normal operation, and occurs when the evaporator liquid level is lower than a low alarm setpoint.
  • a system may respond by posting a warning message.
  • An evaporator liquid level too low alarm is active in normal operation, and occurs when IFS (evaporator low liquid level switch) is closed.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • An evaporator liquid level high warning is active in normal operation, and occurs when the evaporator liquid level is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • An evaporator liquid level too high alarm is active in normal operation, and occurs when 2FS (evaporator high liquid level switch) is open.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a solution inlet pressure low warning is active in warmup and normal operation, and occurs when the solution inlet pressure is lower than a low alarm setpoint.
  • a system may respond by posting a warning message.
  • a solution inlet pressure too low alarm is active in warmup and normal operation, and occurs when the solution inlet pressure is lower than an even lower alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a solution inlet pressure high warning is active in warmup and normal operation, and occurs when the solution inlet pressure is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a solution inlet pressure too high alarm is active in warm up and normal operation, and occurs when the solution inlet pressure is higher than an even higher alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • An evaporator pressure high warning is active in warmup and normal operation, and occurs when the evaporator pressure is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • An evaporator pressure too high alarm is active in warm up and normal operation, and occurs when the evaporator pressure is higher than an even higher alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a condenser pressure high warning is active in warmup and normal operation, and occurs when the condenser pressure is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a condenser pressure too high alarm is active in warm up and normal operation, and occurs when the condenser pressure is higher than an even higher alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor speed too low alarm is active in normal operation, and occurs when the flow rate of the distillate, which can be described as the sum of the condensate flow rate and the product flow rate is less than a setpoint, and when the evaporator pressure is lower than atmospheric pressure.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • An evaporator temperature low warning is active in normal operation, and occurs when the evaporator temperature is lower than a low alarm setpoint.
  • a system may respond by posting a warning message.
  • An evaporator temperature too low alarm is active in normal operation, and occurs when the evaporator temperature is lower than an even lower alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • An evaporator temperature high warning is active in normal operation, and occurs when the evaporator temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • An evaporator temperature too high alarm is active in normal operation, and occurs when the evaporator temperature is higher than an even higher alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a condenser temperature low warning is active in normal operation, and occurs when the condenser temperature is lower than a low alarm setpoint.
  • a system may respond by posting a warning message.
  • a condenser temperature too low alarm is active in normal operation, and occurs when the condenser temperature is lower than an even lower alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a condenser temperature high warning is active in normal operation, and occurs when the condenser temperature is higher than a high alarm setpoint.
  • a system may respond by posting a warning message.
  • a condenser temperature too high alarm is active in normal operation, and occurs when the condenser temperature is higher than an even higher alarm setpoint.
  • a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • a compressor discharge deviation alarm is active in normal operation, and occurs when compressor discharge pressure is significantly lower than a setpoint forXtime.
  • a VFD fault alarm is active in warmup and normal operation, and occurs when a VFD fault is detected.
  • a butanol leak alarm is active in warmup and normal operation, and occurs when butanol is detected.
  • other leak alarms can be provided for other alcohols or solutions, or gases.
  • An emergency stop alarm is active at all steps, and occurs when an emergency stop is detected. For any of these alarms, a system may respond by posting an alarm message, stopping heaters and motor, and going to cooldown.
  • FTIR infrared spectroscopy analytical equipment
  • Such analytical equipment can provide monitoring for an infeed solution 611, or of a solution with an evaporator or condenser chamber, or a distillate leaving a condenser chamber 612, 613.
  • desired thermodynamic conditions of the condenser chamber can be determined by FTIR data in real-time.
  • Variable control elements such a heater and compressor can be automatically adjusted to achieve the desired thermodynamic conditions.
  • Fig. 8 shows an additional embodiment of the invention, including various control relationships.
  • Transducer signals can be conveyed from one or more transducers to a controller 701, which may utilize a PID control algorithm.
  • a transducer that can be used includes a transducer 702 to measure the mass flow rate of a feed coming in. Such a transducer may be utilized prior a feed entering a mixture feed apparatus, such as a feed pump 703, that can control the feed to an E/C core 704.
  • Other examples of transducers include an evaporator pressure sensor 705 and an evaporator temperature sensor 706.
  • a level transducer 701 can be provided within an evaporator 708 to determine the liquid level within the evaporator. Transducers can also be provided to determine condenser temperature 709 and condenser pressure 710.
  • Some embodiments of the invention include a secondary separator 711 that accepts a distillate from an E/C core and separates the distillate into a product 712 and a condensate 713.
  • Transducers are provided to measure the mass flow rate of the product 714 and to measure the mass flow rate of the condensate 715.
  • the product can be a vapor component of a distillate which can have a higher alcohol content, and a condensate can be a liquid component of a distillate which can mostly be made up of water.
  • Transducers are also provided to measure the temperature 716 and pressure 717 of the condensate.
  • Any of the transducers can communicate the various measurements to a controller 701.
  • a controller 701 can utilize various control algorithms to maintain various characteristics in desired ranges or setpoints. If a transducer signal indicates that a characteristic is not within a desired range or setpoint, a controller 701 provides a response signal to a control point to regulate the characteristic to the desired range or setpoint. Similarly, if a transducer signal indicates that a characteristic is within a desired range or setpoint, the controller provides a response signal to a control point to maintain the characteristic at the desired range or setpoint.
  • a controller 707 controls the operation of control points, which may include a feed pump 703, a compressor 721, a heater 718, or a heat exchanger 719.
  • a control point can include a feed pump 703.
  • the feed pump controls the flow rate of a feed solution.
  • Other mixture feed apparatuses such as a valve, can be used as a control point.
  • a response signal from a controller 701 can communicate with a VFD 720, which can dictate the operation of the feed pump.
  • a mass flow rate is used as a control parameter and uses real time concentration analysis (such as FTIR). Using FTIR, a mass flow rate can be easily calculated.
  • a compressor 721 which is in fluid communication with an evaporator 708 and a condenser 725.
  • a compressor 721 may vary a CDP based on the speed of the compressor motor.
  • the controller PLC
  • the VFD sends motor speed (Hz) feedback to the controller, which in turns sends a command to the VFD to regulate the motor speed.
  • a controller 701 may separately, or in addition communicate with a current transducer 722 to regulate compressor motor speed.
  • One or more heater 718 providing heat to an evaporator and/or condenser of an E/C core 704 is another example of a control point.
  • a controller 701 may send a response signal to a heater relay 723 that controls the operation of the heater 718. Another control point may be provided by one or more secondary exchangers 719 that may reduce or provide heat to a secondary separator 711 that separates a distillate from a condenser 725. A response signal from a controller 701 can communicate with a secondary heat exchanger relay 724 to control operation of the secondary heat exchanger 719.
  • control points can be provided which may affect characteristics of the system.
  • a control point can be a device to determine a concentration or composition of feed to provide to the E/C core.
  • a mixture feed apparatus can control which feed solution or combinations thereof is provided to an E/C core.
  • a controller can send a responsive signal to indicate the feed solution composition or concentration.
  • the control points can require work or energy inputs.
  • a feed pump and a compressor require work input to operate.
  • a heater requires energy input, such as heat energy input.
  • a heat exchanger can have energy input or output, such as heat energy input or output for various components. Energy losses, such as heat loss occur throughout the system.
  • Various operating units are provided in a VCD system, including, but not limited to: a mixture feed apparatus, such as a feed pump or control valve to maintain a liquid level within an evaporator, an E/C core, a compressor, or a secondary separator.
  • a mixture feed apparatus such as a feed pump or control valve to maintain a liquid level within an evaporator, an E/C core, a compressor, or a secondary separator.
  • a VCD unit can be utilized in a multistage VCD process.
  • multiple VCD units are in thermal communication with one another.
  • the heat exchange between the multiple VCD units provides coupled means of altering thermodynamic conditions of the evaporators and condensers of these systems.
  • the control measures discussed herein may be adapted and apply to a multistage VCD process. For instance, control schemes may be provided to control one or more control points, such as variable speed compressors, communicating with one or more VCD units to optimize the overall multistage process.
  • Figure 9 illustrates the effect of evaporator pressure PT EVAP on product concentration.
  • butanol concentration was increased by lowering the evaporator pressure from a default value of 0.65 psig to a user defined value of 0.10 psig through a decrease in applied heat.
  • PT EVAP was maintained above zero in order to produce distillate.
  • an evaporator pressure of 0.10 was chosen, which is sufficiently low to concentrate butanol, but sufficiently high to maintain distillation.
  • PT EVAP was lower toward 0.10 psig
  • butanol concentration approached a maximum of approximately 38% [v/v].
  • butanol concentration was optimized, but other values such as energy consumption or recovery yield could be optimized in a similar fashion.

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Abstract

L'invention porte sur des systèmes et des procédés de régulation thermodynamique d'une distillation à compression de vapeur. Des éléments à régulation variable, tels qu'un compresseur à vitesse variable ou un réchauffeur, sont régulés de façon à fournir les conditions thermodynamiques souhaitées à une partie d'une unité de distillation à compression de vapeur. Les conditions thermodynamiques souhaitées sont déterminées sur la base d'objectifs d'optimisation. Des capteurs assurent une rétroaction vers un régulateur, qui commande les éléments à régulation variable.
PCT/US2010/032462 2009-04-28 2010-04-26 Régulation thermodynamique d'une distillation à compression de vapeur WO2010126847A1 (fr)

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WO2014130352A1 (fr) * 2013-02-21 2014-08-28 Butamax Advanced Biofuels Llc Récupération d'énergie thermique destinée à servir de source de chaleur dans le cadre de la production de butanol à partir d'un processus de fermentation
CN106693413A (zh) * 2017-03-07 2017-05-24 内蒙古碳谷科技有限公司 一种稳定的小流量液体蒸发系统及其蒸发工艺
WO2020167871A3 (fr) * 2019-02-11 2020-09-24 Amantsy, Inc. Système de distillation totalement régénérative pour le dessalement d'eau à faible coût
US10823176B2 (en) 2018-08-08 2020-11-03 Fluid Handling Llc Variable speed pumping control system with active temperature and vibration monitoring and control means

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WO2014130352A1 (fr) * 2013-02-21 2014-08-28 Butamax Advanced Biofuels Llc Récupération d'énergie thermique destinée à servir de source de chaleur dans le cadre de la production de butanol à partir d'un processus de fermentation
CN106693413A (zh) * 2017-03-07 2017-05-24 内蒙古碳谷科技有限公司 一种稳定的小流量液体蒸发系统及其蒸发工艺
US10823176B2 (en) 2018-08-08 2020-11-03 Fluid Handling Llc Variable speed pumping control system with active temperature and vibration monitoring and control means
WO2020167871A3 (fr) * 2019-02-11 2020-09-24 Amantsy, Inc. Système de distillation totalement régénérative pour le dessalement d'eau à faible coût
CN113423666A (zh) * 2019-02-11 2021-09-21 阿曼特希股份有限公司 用于低成本水脱盐的完全再生蒸馏系统
EP3924302A4 (fr) * 2019-02-11 2022-11-16 Amantsy, Inc. Système de distillation totalement régénérative pour le dessalement d'eau à faible coût
CN113423666B (zh) * 2019-02-11 2023-10-27 阿曼特希股份有限公司 用于低成本水脱盐的完全再生蒸馏系统

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