Abstract:
A process for removing water from solid material ( 10 ) using liquid-solid extraction and liquid-liquid extraction in an extraction system ( 100 ). Multiple solvents are used sequentially to replace the water with a first solvent, then replacing that solvent with a second solvent, etc., then eventually removing the last solvent from the solid materials. The solvents have progressively lower heats of vaporization, enthalphy of vaporization, boiling point or related property, so as to conserve use of thermal energy.

Description:
This application is a National Stage of PCT International Patent Application No. PCT/US2003/040646 filed Dec. 19, 2003, which claims benefit to U.S. Provisional Application Ser. No. 60/435,015 filed Dec. 19, 2002, and which application(s) are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention is directed to a system, and its methods of use, for extracting liquid water and/or a hydrocarbon from a feed stream using at least two solvents. The system and method can generally be described as a reduced energy extraction and drying processes. 
     BACKGROUND OF THE INVENTION 
     For many processes, an exiting stream, whether considered a waste stream, a by-product, or the main desired stream, is composed of a solid material wet with water. This water is typically found in both the interstitial spaces of the solid and is absorbed or adsorbed by the solid. Water such as this has typically been removed by drying the solids with thermal energy. This process generally requires a large amount of heat or energy to remove the water from the solids and obtain dry, usable solids. 
     Attempts have been made to use organic solvents to remove water from wet solids using solvents such as hexane. Essentially, the hexane is used to displace the water from the solids. The hexane remaining with the solids is then evaporated from the solids with thermal energy. Again, this process generally requires a large amount of thermal energy, but less than if water alone was being dried from the solids. However hexane also brings with it certain other concerns, such as toxicity. Further, because of poor displacement, large amounts of residual water may remain with the solids. 
     Some examples of known extraction methods include Baird, U.S. Pat. No. 4,251,231, which utilizes liquid-liquid extraction to directly extract alcohol suitable for use in gasohol from a fermentation mixture. Gasoline was used as the extraction solvent. The water was removed by either the use of adsorbents or absorbents, or by chilling the extracted alcohol-gasoline product to a temperature below about −10° F., thereby removing the water. 
     During the ethanol manufacturing process, solids, wet with primarily water and some ethanol, exit the fermentation process as a beer stream. Other materials, such as oils and glycerol are also present in the beer stream. It is desired to obtain individual output streams of dry solids, water, and ethanol. 
     The beer stream solids, as discussed above, have the water in both the interstitial spaces of the solid and that which is absorbed or adsorbed by the solid. This water, and any ethanol, has typically been removed by drying the solids with thermal energy. Preferably, the ethanol is recovered and is used; unfortunately, recovery of pure, or fairly pure ethanol, is not usual. Additionally, preferably the water is sufficiently pure that the water can be readily disposed; unfortunately, the water has contaminants that inhibit direct, unmanaged disposal. Still further, contaminants, such as oils and glycerol, remain in the solids, making them undesirable for many applications. 
     What is needed is a low cost, more heat or energy efficient process for drying solids wet with water. It would be beneficial if the various output streams from the process could be reclaimed and used. 
     SUMMARY OF THE INVENTION 
     The invention is a process for separating water from solids and from other hydrocarbons that may be present, the process utilizing at least 20% less energy than conventional forced air drying of the same material. 
     Solids, wetted with water, are separated from the water and dried by the inventive process. The process removes the water residing in the interstitial spaces of the solids, as well as some of the water that has been absorbed by the solids. The process uses a liquid-solid extraction process to remove the water from the solid feed stream. 
     In one embodiment, multiple solvents are used to step-wise remove the water from the solids and obtain dry solids. The multiple solvents facilitate the removal of the water from the solids, by step-wise replacing the water with a solvent, replacing that solvent with a further solvent, and then eventually removing the further solvent from the solids. Use of multiple solvents facilitates the separation of the initial solvent from the water and from the various solvents used in further processing. The multiple solvents are separated from each other by liquid-liquid extraction or distillation processes. 
     Multiple solvents utilize less thermal energy to dry the solids and separate the solvents than conventionally used in drying processes. The first solvent selected has a lower heat of vaporization, enthalpy of vaporization, boiling point, or other such physical property, than water. Each subsequent solvent has a still lower heat of vaporization, enthalpy of vaporization, boiling point, or other such physical property than the previous solvent used. 
     In a further embodiment, the invention is directed to a process for drying solids initially wet with water. The process includes contacting a feed stream comprising solids having interstitial spaces, and water present in the interstitial spaces, with a first solvent. The water present in the interstitial spaces is displaced by the first solvent, leaving the first solvent in the interstitial spaces. The feed stream having the first solvent in the interstitial spaces is then contacted with a second solvent; and the first solvent present in the interstitial spaces is displaced by the second solvent, thus providing the second solvent in the interstitial spaces. 
     In another embodiment, the process includes providing an ethanol source stream and an n-propyl bromide source stream. The water present in the interstitial spaces is displaced by the ethanol, leaving ethanol in the interstitial spaces. The ethanol in the interstitial spaces is then displaced by n-propyl bromide, leaving n-propyl bromide in the interstitial spaces. The n-propyl bromide is removed from the solids by the application of heat. In a preferred embodiment, an alcohol product that is at least 90% pure ethanol is obtained. 
     In yet another embodiment, the process includes providing an ethanol source stream and an ether source stream. The water present in the interstitial spaces is displaced by the ethanol, leaving ethanol in the interstitial spaces. The ethanol in the interstitial spaces is then displaced by ether, leaving ether in the interstitial spaces. The ether is removed from the solids by the application of heat. In a preferred embodiment, an ether product that is at least 95% pure ether is obtained. Alternately or additionally, an alcohol product that is at least 90% pure ethanol is obtained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a general process according to the present invention, having an ‘initial’ separation subprocess, a ‘solvent-from-solids’ separation subprocess and a ‘water-from-solvents’ separation subprocess. 
         FIG. 2  is a schematic process diagram of a general, first embodiment of the ‘introductory’ separation subprocess according to the present invention. 
         FIG. 3A  is a schematic diagram of an extraction unit of the subprocess of  FIG. 2 ; 
         FIG. 3B  is an enlarged, perspective view of a portion of the extraction unit of  FIG. 3A ; 
         FIG. 4  is a schematic process diagram of a first embodiment of the ‘solvent-from-solids’ separation subprocess according to the present invention; 
         FIG. 5  is a schematic process diagram of a portion of the ‘solvent-from-solids’ separation subprocess of  FIG. 4 . 
         FIG. 6  is a schematic process diagram of a first embodiment of the ‘water-from-solvents’ separation subprocess according to the present invention. 
         FIG. 7  is a schematic process diagram of a preferred process according to the present invention. 
         FIG. 8  is a schematic diagram of an alternate process according to the present invention. 
         FIG. 9  is a schematic diagram of another alternate process according to the present invention. 
         FIG. 10  is a schematic diagram of yet another alternate process according to the present invention. 
         FIG. 11  is a binary diagram for a preferred three-solvent system according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As provided above, the invention is directed to processes for separating water from solids by utilizing at least two solvents. The process uses a first solvent to displace the water from the interstitial spaces in the solids. This first solvent, having a lower heat of vaporization and boiling point than the water, is easier to remove from the solids than water. A second solvent is used to displace the first solvent from the solids. The second solvent has a lower heat of vaporization and boiling point than the first solvent. 
     The first solvent is preferably soluble in water but preferably does not form an azeotropic mixture with water. An azeotropic mixture is a mixture of two or more substances that behaves like a single substance. The vapor produced by partial evaporation of the liquid has the same composition as the liquid; that is, vaporization of the mixture does not result in separation of the initial substances. 
     The second solvent is preferably soluble with the first solvent but insoluble with water. Additionally, the first and second solvents should preferably not form an azeotropic mixture. 
     Any third, or subsequent solvent, is preferably soluble with the predecessor solvent, but not form an azeotropic mixture with the predecessor solvent. 
     By utilizing this multiple solvent, liquid-extraction process, the energy needed to dry the solids and to separate the various solvents from each other and from water, is greatly reduced compared to conventional processes. 
     The processes of the invention can generally be reduced to an initial extraction subprocess that removes water from the solids followed by two subprocesses, a ‘solvent-from-solids’ separation subprocess which separates solvent from the solids, and a ‘water-from-solvents’ separation subprocess that separates and reclaims the water and solvents, and optionally, other components. 
     Referring now to the figures, a diagrammatic rendering of the process according to the present invention is generally depicted in  FIG. 1 . This process has an initial separation process  100  to separate water from the solids and two general subprocesses, one for removing solvent from solids, subprocess A, and a second for separating and reclaiming water and solvents, subprocess B. 
     Feed stream  10 , an aqueous stream with solids therein, is illustrated entering the system at the top left corner of  FIG. 1 . The type and amount of solids in stream  10  will vary. The specific solids present will depend on the source, and example sources include grains, other plant materials and earthen materials. 
     The amount of solids in stream  10  is generally 5 to 50% by weight. A common amount of solids in stream  10  is about 10-12%. As mentioned, steam  10  is typically an aqueous stream, with the water present at a level of about generally 50 to 95% by weight. A common amount of water in stream  10  is about 78 wt-%. Other liquids, in addition to the water, can be and are often present in feed stream  10 . 
     If feed stream  10  is from a fermentation process, stream  10  generally includes alcohol (such as ethanol). The level of alcohol and other components in stream  10  is dependent on the efficiency of the process providing stream  10 , however, the alcohol in stream  10  is generally less than 16 wt-%. Usually, the level of alcohol in stream  10  is greater than about 8 wt-%. A common level of alcohol in some streams is about 15 wt-%. 
     Other materials are typically present in stream  10 . For example, oil (such as corn oil) and glycerol are usually present. Examples of solutes that may be present include acids (such as acetic acid), aldehydes (such as acetaldehyde), and various sugars. The levels of these material are low, typically less than 2 wt-% and often less than 1 wt-% of stream  10 . 
     Returning to  FIG. 1 , feed stream  10  is fed into a water/solid extraction system  100  where the solids of feed stream  10  are separated from water. An alternate descriptive term for water/solid extraction system  100  is a water extractor or a solid-liquid extraction unit. Extraction system  100  is configured to remove water from feed stream  10  and replace the water with a solvent. Additional details regarding a preferred extraction system  100  are provided below. 
     Extraction system  100  transfers one or more components from feed stream  10  into the extraction solvent stream (described below). Typically, extraction system  100  operates in a counter-current arrangement; that is, the extraction solvent stream enters system  100  farthest from where feed stream  10  enters, and the two streams contact and pass counter-currently to each other. 
     In addition to feed stream  10  being fed into extraction system  100 , an extraction solvent stream  15  is fed into system  100 . It is the solvent in stream  15  that will extract and replace the water from feed stream  10 . First solvent from stream  15  combines with or displaces the original aqueous liquids from feed stream  10  as feed stream  10  and solvent stream  15  pass in system  100 . 
     This exchange of one solvent for another in a stream is due to concentration equilibrium. Solvent, present at a high concentration in stream  15 , moves to a stream having a lower concentration, i.e., stream  10 ; likewise, water, present at a high concentration in stream  10 , moves to a stream with a lower concentration of water, i.e., stream  15 . 
     The solvent is selected for stream  15  based on a lower heat of vaporization or enthalpy of vaporization than the water in feed stream  10 . Water has a heat of vaporization of 1000 BTU per pound of water, thus, solvent of stream  15  should have a heat of vaporization less than 1000. The lower the heat of vaporization in relation to 1000 BTU, the easier the subsequent separation of solvent  15  from water. Preferably, the solvent of stream  15  is water soluble, however, it is preferred that the solvent of stream  15  and water do not form an azeotropic mixture, so that subsequent separation of the solvent and water is simple. 
     Although virtually any water soluble solvent can be selected for extraction solvent stream  15 , it is preferred to select one which may already be present in feed stream  10 . Examples of suitable solvents include alcohols (such as ethanol, methanol, isopropyl alcohol, and gasohol) and ketones (such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK)). If feed stream  10  is primarily solids, water and alcohol, as it is from many fermentation processes, solvent stream  15  is preferably an alcohol, more preferably the alcohol that is present in feed stream  10 . 
     As stated above, water in feed stream  10  is replaced with first solvent from stream  15  by water extraction system  100 . The resulting output streams from system  100  are solids stream  20  and liquid stream  30 . 
     Solid stream  20  is a wet solids stream, composed of the solids from stream  10  and an amount of first solvent from stream  15 . Wet solids stream  20  progresses to and is treated by subprocess A, as will be described below. Liquid stream  30  is generally composed of the original liquid from feed stream  10  (that is, the water and any other liquid, such as an alcohol) and the solvent from solvent stream  15 . Liquid stream  30  progresses to and is treated by subprocess B, described below. 
     Extraction System  100   
     A preferred configuration for a water-solid extraction system  100  is illustrated in  FIG. 2 . As seen in  FIG. 1  and in  FIG. 2 , feed stream  10  and solvent stream  15  enter system  100 , and wet solids stream  20  and liquid stream  30  exit system  100 . 
     Water-solid extraction system  100  has at least one extraction unit  110 . In the system  100  illustrated in  FIG. 2 , system  100  has three extraction units, specifically,  110 A,  110 B,  110 C. Each extraction unit  110  includes a mixing tank  112 , a pump  114 , mechanical separator  116 , and the piping to operably connect the elements. 
     Mixing tank  112  can be any suitable receptacle for combining and temporarily storing solid and liquid materials. In the embodiment illustrated, tank  112  accepts beer feed  10  and water/solvent stream  31 , which will be described below. Examples of suitable materials for tank  112  include steels, such as carbon steel and stainless steels. A preferred material is 304 stainless steel. The volume of tank  112  is based on the material flow volumes and desired residence time in tank  112 . A 30 gallon tank is a suitable size for some processes. 
     Pump  114 , used to move material from tank  112 , is positioned downstream of tank  112 . Pump  114  is selected for its ability to move the material from tank  112 , which includes solid material and liquid, to mechanical separator  116 . Examples of suitable pumps include diaphragm pumps, centrifugal pumps, and pumps designed to pump a combination of liquid and solids. An example of a preferred pump  114  is a centrifigal pump available from Goulds Pumps of ITT Industries. 
     Mechanical separator  116  separates solid material from liquid. Examples of suitable mechanism separating equipment include Rotocel extractors, double screw extractors, baskets, rotary perforated belts, sliding rolls, and loop extractors; this equipment is well known for solid/liquid extraction processes. The specific equipment used will be dependent on the solvents used in the process and in the solvent ratios. Preferred equipment for use in extraction system  100  is a stationary screen, described below. 
     The piping connecting tank  112 , pump  114 , and mechanical separator  116 , for each extraction unit  110 , is selected for its ability to move the solid-liquid material. An example of preferred piping is 1 inch carbon steel piping. 
     A preferred configuration for a screen mechanical separator  116  is illustrated in  FIG. 3A . Separator  116  has a housing  1162  in which is a screen  1163 . Screen  1163  has a first, curved portion  1163 A and a second, generally vertical portion  1163 B. Screen  1163  separates housing  1162  into a filtrate side  1167  and a cake side  1168 . 
     A nozzle  1164  is present to spray wet solids stream  11 , from tank  112 , onto screen  1163 . In one preferred process configuration, nozzle  1164  is configured to provide a flow of 8-10 gallons/minute of wet solids stream  11  onto screen  1163 . 
     An enlargement of screen  1163  is illustrated in  FIG. 3B . Screen  1163  has a plurality of separating members  1165  secured by cross-members  1166 , both of which can be carbon steel or stainless steel. Separating members  1165 , positioned closer to nozzle  1164 , on cake side  1168 , preferably extend vertically, to facilitate solids running down members  1165 . In one preferred process, members  1165  and  1166  are arranged to provide a mesh size (i.e., an opening) of at least 0.01 inch. 
     Wet solids stream  11 , sprayed by nozzle  1164  primarily onto curved portion  1163 A, is separated by members  1165  and  1166 . Liquid from stream  11  passes through screen  1163  and is collected on filtrate side  1167 . The solids, too large to pass through screen  1163 , remain on cake side  1168 . 
     It is understood that some liquid will not pass through screen  1163  but will remain with the solids. Screen  1163  may have a dam or baffle  1169  positioned at or near the juncture of curved portion  1163 A and vertical portion  1163 B, to retain solids in an attempt to have liquid drop therefrom. 
     The liquid, having passed through screen  1163  to filtrate side  1167 , would be removed from housing  1162  via an outlet  1167 A. The wet solids, left on cake side  1168 , would be removed from housing  1162  via an outlet  1168 A. 
     Returning to  FIG. 2 , the illustrated process has three extraction units  110 A,  101 B,  110 C. Unit  110 A has mixing tank  112 A, pump  114 A, mechanical separator  116 A, and the piping to operably connect the elements. Unit  110 B has mixing tank  112 B, pump  114 B, mechanical separator  116 B, and the piping to operably connect the elements. Unit  110 C has mixing tank  112 C, pump  114 C, mechanical separator  116 C, and the piping to operably connect the elements. 
     Beer feed  10  is fed into tank  112 A where it is mixed with water/solvent stream  31  (described later). This mixture, as stream  11 , is pumped via pump  114 A to mechanical separator  116 A, where it is split into water/solvent stream  30  and wet solids stream  34 . 
     Wet solids stream  34  is fed into tank  112 B where it is mixed with water/solvent stream  32  (described later). This mixture, as stream  12 , is pumped via pump  114 B to mechanical separator  116 B, where it is split into water/solvent stream  31  and wet solids stream  35 . 
     Wet solids stream  35  is fed into tank  112 C where it is mixed with first solvent stream  15 . This mixture, as stream  13 , is pumped via pump  114 C to mechanical separator  116 C, where it is split into water/solvent stream  32  and wet solids stream  20 . 
     Stream  30 , from unit  110 A, is referred to as a “full miscella”. In the embodiment illustrated in  FIG. 2 , because there are three units, each stream is allotted a third (i.e., ⅓) designation. Stream  31 , from unit  110 B, is referred to as a “⅔ miscella” and stream  32 , from unit  110 C, is referred to as a “⅓ miscella”. Full miscella stream  30  has a lower solvent concentration and a higher water concentration than ⅔ miscella stream  31 , which has a lower solvent concentration and a higher water concentration than ⅓ miscella stream  32 . 
     Each of these stream  30 ,  31 ,  32  is reused in the process. Stream  31  is recycled and fed into tank  112 A, and stream  32  is recycled and fed into tank  112 B. Full miscella stream  30 , composed of water from beer feed  10  and first solvent from stream  15 , is used in ‘water-from-solvents’ separation subprocess B. Wet solids stream  20 , composed of solids and first solvent from stream  15 , progresses to ‘solvent-from-solids’ separation subprocess A. 
     ‘Solvent-from-Solids’ Separation Subprocess A 
     Returning to  FIG. 1 , from water extraction system  100 , wet solids stream  20  is conveyed to ‘solvent-from-solids’ separation subprocess A. In subprocess A, solvent from wet solids stream  20  is removed, by using a second solvent, to obtain dry solid stream  90 . Second solvent is introduced to subprocess A as stream  70 . First solvent (originally from stream  15 ) and second solvent from stream  70  depart subprocess A as stream  80 / 230 . 
     In subprocess A, the first solvent from stream  15 , such as an alcohol, is extracted from the solids and replaced with a second solvent. The second solvent is removed from the solids and dry solids are obtained. ‘Solvent-from-solids’ separation subprocess A is generally configured as two sub-subprocess, solvent extraction and thermal drying. 
     Referring to  FIG. 4 , ‘solvent-from-solids’ separation subprocess A is illustrated having solvent extraction system  200  and drying system  300 . An alternate descriptive term for solvent extraction system  200  is a solvent extractor or a solid-liquid or solid-solvent extraction unit. Solvent extraction system  200  is configured to remove the first solvent from wet solids stream  20  and replace the first solvent with a second solvent. 
     Solvent extraction system  200  transfers one or more components from wet solids stream  20  into the extraction second solvent stream (described below). Typically, solvent extraction system  200  operates in a counter-current arrangement. 
     In addition to wet solids stream  20  being fed into extraction system  200 , an extraction second solvent stream  70  is fed into system  200 . It is the solvent in stream  70  that will extract and replace the solvent from wet solids  20 . Second solvent from stream  70  combines with or displaces the first solvent from feed stream  15  in solids stream  20  as stream  20  and solvent stream  70  pass in system  200 . 
     The second solvent is selected for stream  70  based on a lower heat of vaporization or enthalpy of vaporization than the first solvent of stream  15 , which is present in wet solids stream  20 . Preferably, the solvent of stream  70  is soluble with and miscible with the first solvent of stream  15 , however, it is preferred that the solvent of stream  70  and the solvent of stream  15  do not form an azeotropic mixture, so that subsequent separation of the solvents is simple. 
     Examples of suitable solvents for stream  70  include ethers, (such as ethyl ether, MTBE (methyl tert-butyl ether), ETBE (ethyl tert-butyl ether), fluorinated ethers, and other low molecular weight ethers), halogenated hydrocarbons (n-propyl bromide or 1-bromopropane, commercially available under the trade name “Hypersolve NPB”), straight chain low molecular hydrocarbons (such as hexane, pentane), and low molecular weight aromatic hydrocarbons (such as toluene, benzenes, xylenes). 
     The second solvent is selected on the basis of high solubility with the first solvent (e.g., ethanol), low solubility with water, and ease of separation between the first and second solvents, generally based on differential of heat of vaporization or enthalpy of vaporization. 
     Stream  70  may be provided by an external source, but is preferably recycled from the solvent removed from the solids, and from overhead stream  70  from still  700 , as will be discussed below. 
     As stated above, first solvent from stream  15 , now present in wet solids stream  15 , is replaced with second solvent from stream  70  by solvent extraction system  200 . The resulting output streams from system  200  are wet solids stream  220  and liquid stream  230 ; see  FIG. 4 . Solid stream  220  is composed of the solids and an amount of second solvent from stream  70 . Wet solids stream  220  progresses to drying system  300 , where the second solvent is removed from the solid. 
     Liquid stream  230  is generally composed of the solvent from solvent stream  15  and second solvent from stream  70 . Liquid stream  230  progresses to and is treated by subprocess B, described below. 
     Solvent Extraction System  200   
     A preferred configuration for a solvent-solid extraction system  200  is illustrated in  FIG. 5 . As seen in  FIG. 4  and in  FIG. 5 , wet solids stream  20  and second solvent stream  70  enter system  200 , and wet solids stream  220  and liquid stream  230  exit system  200 . 
     Solvent-solid extraction system  200  has at least one extraction unit  210 . In the system  200  illustrated in  FIG. 5 , system  210  has three extraction units, specifically,  210 A,  210 B,  210 C. Each extraction unit  210  includes a mixing tank  212 , a pump  214 , mechanical separator  216 , and the piping to operably connect the elements. 
     Mixing tank  212  can be any suitable receptacle for combining and temporarily storing solid and liquid materials. In the embodiment illustrated, tank  212  accepts wet solids stream  20  and liquid stream  41 , which will be described below. Examples of suitable materials for tank  212  include steels, such as carbon steel and stainless steels. A preferred material is 304 stainless steel. The volume of tank  212  is based on the material flow volumes and desired residence time in tank  212 . A 30 gallon tank is a suitable size for some processes. 
     Pump  214 , used to move material from tank  212 , is positioned downstream of tank  212 . Pump  214  is selected for its ability to move the material from tank  212 , which includes solid material and liquid, to mechanical separator  216 . Examples of suitable pumps include diaphragm pumps, centrifugal pumps, and pumps designed to pump a combination of liquid and solids. An example of a preferred pump  214  is a centrifugal pump available from Goulds Pumps of ITT Industries. 
     Mechanical separator  216  separates solid material from liquid. Examples of suitable mechanism separating equipment include Rotocel extractors, double screw extractors, baskets, rotary perforated belts, sliding rolls, and loop extractors; this equipment is well known for solid/liquid extraction processes. The specific equipment used will be dependent on the solvents used in the process and in the solvent ratios. Preferred equipment for use in extraction system  200  is a stationary screen, described below. 
     The piping connecting tank  212 , pump  214 , and mechanical separator  216 , for each extraction unit  210 , is selected for its ability to move the solid-liquid material. An example of preferred piping is 1 inch carbon steel piping. 
     A preferred configuration for a screen mechanical separator  216  is illustrated in  FIG. 3A  as separator  116 ; that is, mechanical separator  216  can be the same as mechanical separator  116  from water extraction system  100 . 
     Returning to  FIG. 5 , the illustrated process has three extraction units  210 A,  2101 B,  210 C. Unit  210 A has mixing tank  212 A, pump  214 A, mechanical separator  216 A, and the piping to operably connect the elements. Unit  210 B has mixing tank  212 B, pump  214 B, mechanical separator  216 B, and the piping to operably connect the elements. Unit  210 C has mixing tank  212 C, pump  214 C, mechanical separator  216 C, and the piping to operably connect the elements. 
     Wet solids stream  20  is fed into tank  212 A where it is mixed with liquid stream  41  (described later). This mixture, as stream  21 , is pumped via pump  214 A to mechanical separator  216 A, where it is split into liquid stream  230  and wet solids stream  44 . 
     Wet solids stream  44  is fed into tank  212 B where it is mixed with liquid stream  42  (described later). This mixture, as stream  22 , is pumped via pump  214 B to mechanical separator  216 B, where it is split into liquid stream  41  and wet solids stream  45 . 
     Wet solids stream  45  is fed into tank  212 C where it is mixed with second solvent stream  70 . This mixture, as stream  23 , is pumped via pump  214 C to mechanical separator  216 C, where it is split into liquid stream  42  and wet solids stream  220 . 
     Liquid stream  230 , from unit  210 A, is referred to as a “full miscella”. Stream  41 , from unit  210 B, is referred to as a “⅔ miscella” and stream  42 , from unit  210 C, is referred to as a “⅓ miscella”. Full miscella stream  230  has a lower second solvent concentration and a higher first solvent concentration than ⅔ miscella stream  41 , which has a lower second solvent concentration and a higher first solvent concentration than ⅓ miscella stream  42 . 
     Each of these streams  230 ,  41 ,  42  is reused in the process. Stream  41  is recycled and fed into tank  212 A, and stream  42  is recycled and fed into tank  212 B. Full miscella stream  230 , composed of first solvent from stream  15  and second solvent from stream  70 , is used in ‘water-from-solvents’ separation subprocess B. Wet solids stream  220 , composed of solids and second solvent from stream  70 , progresses to drying system  300 . 
     Drying System  300   
     Wet solids stream  220 , having solids and second solvent from stream  70 , from solvent extraction system  200 , is fed to drying system  300 , where the solvent and any other volatile liquids or solvents are removed from the solids. Drying system  300  is the only unit in ‘solvent-from-solids’ separation subprocess A that uses thermal energy. Examples of suitable equipment for drying system  300  include a steam-jacketed tube dryer (such as a Schnecken tube dryer), steam-heated-screw tube dryer, a rotary dryer, a belt dryer, a down-draft desolventizer, or a DT; this equipment is well known for drying processes. A preferred drying system  300  includes a steam-jacketed tube style dryer. 
     The solvent is thermally removed from the solids at drying system  300 , and dry solids are obtained as output stream  90 . The second solvent removed exits drying system  300  as stream  80 . Stream  80  may be further processed. In the process embodiment illustrated in  FIG. 4 , stream  80  is combined with miscella stream  230  and sent to ‘water-from-solvents’ separation subprocess B. 
     ‘Water-from-Solvents’ Separation Subprocess B 
     Returning to  FIG. 1 , stream  30 , composed of water from beer feed  10  and first solvent from stream  15 , is conveyed to ‘water-from-solvents’ separation subprocess B and processed to separate the water from solvent. 
     However, to maximize the separation to provide desired output streams, subprocess B preferably utilizes a second solvent, provided to subprocess B as solvent stream  40 . 
     Solvent of stream  40  is selected to have a lower heat of vaporization or enthalpy of vaporization than the components of stream  30 , that is, the water from feed stream  10  and the solvent of stream  15 . In a preferred method, the solvent of stream  40  is the same as the solvent of stream  70 , from ‘solvent-from-solids’ separation subprocess A, described above. Preferably, solvent stream  40  is recycled from ‘solvent-from-solids’ separation subprocess B; specifically, solvent stream  40  is obtained from stream  80 . 
     Stream  80  is combined with stream  230  and this combined stream  80 / 230  is fed as a single stream to subprocess B. Stream  40  is added as necessary to assure a proper concentration of the three major components, water, first solvent and second solvent. 
     Any known methods can be used to separate the water from the solvent. Examples of suitable liquid-liquid extraction or liquid-liquid separation methods include distillation, for example packed, York-Scheibel, Oldshue-Ruston, rotating disc, Karr or pulsed columns. Another suitable separation method is with a centrifugal contactor. 
     One general configuration for ‘water-from-solvents’ separation process B is illustrated in  FIG. 6 . Subprocess B includes a liquid-liquid separation unit  400  and two distillation units  500 ,  600 . 
     In this embodiment, liquid stream  30 , which enters liquid-liquid process unit  400  at the bottom, has a density less than stream  80 / 230  which enters at the top of unit  400 . Thus the components of stream  30  rise in unit  400  while components in stream  80 / 230  fall in the column. Exiting from unit  400  are top stream  45  from the top of unit  400  and a bottom stream  65  from the bottom of unit  400 . The particular composition of streams  45 ,  65  will depend on the composition of streams  30  and  80 / 230 . Stream  40  is a make-up stream to assure proper balance of water, first solvent and second solvent in unit  400 . 
     There are components in each entering stream  30 ,  40  that are soluble in one another and some that are insoluble in each other. By choice, the solvent of stream  80 / 230  and water are typically not soluble in each other and form an upper and lower phase rich in one or the other. As the solvent may have a density greater or lesser than that of water, the water rich phase may be at the top or bottom. If the solvent of stream  80 / 230  is assumed to have a density of 1.3, and therefore denser than water, the solvent rich phase will exit out the bottom of the column  400  as stream  65  and the water-rich phase out the top as stream  45 . Stream  45  tends to be a stream high in alcohol and water with other lesser water-soluble components, possibly with a small amount of the solvent of stream  80 / 230 . Stream  65  is a stream high in solvent, with possibly small amounts of alcohol and other components. 
     Stream  45  is sent to process unit  500 , an evaporation or distillation device, for further separation into streams  55  and  60 . Stream  65  is sent to process unit  600 , a different distillation or evaporation device, for further separation into streams  50  and  75 . 
     In many processes, streams  50 ,  55 ,  60 ,  75  are sufficiently pure so that the material from these streams can be sold or otherwise used without the need for additional processing. 
     A Preferred Embodiment of the Process 
     A preferred embodiment of the process is diagrammatically illustrated in  FIG. 7 . This process has an initial extraction process that removes the water from the solids followed by two subprocesses. The first subprocess removes the initial solvent from the solids and a second subprocess that separates and reclaims the water, solvent and other components. The description of this preferred process uses the same reference numerals used before for like streams and equipment, as appropriate, except that the reference numerals are followed by an “a”. 
     In this embodiment of a preferred process, a beer stream  10   a  (composed of corn solids, water, ethanol, oils, glycerol and other minor components) is fed into a solid-liquid extraction system  100   a . An alternative term for solid-liquid extraction system  100   a  is a water extractor or water extraction unit. Water extraction system  100   a  is designed to remove water from the feed stream  10   a  and replace the water with a solvent. Examples of suitable solids-liquid extraction equipment have been described previously as water extraction system  100 , and a preferred system  100   a  includes three separators  116 . The water-extraction system  100   a  operates in a counter-current fashion. 
     A first solvent, an extraction solvent,  15   a  is fed into water extraction system  100   a  where part of the solvent replaces the water from stream  10   a . In this embodiment, the extraction solvent is ethanol. Ethanol has a lower heat of vaporization or enthalpy of vaporization than the water in feed stream  10   a.    
     System  100   a , the resulting output streams are wet solids stream  20   a  and liquid stream  30   a . Solid stream  20   a  progresses to and is treated by ‘solvent-from-solids’ separation subprocess A, described below. Liquid stream  30   a  progresses to and is treated by ‘water-from-solvents’ separation subprocess B, also described below. 
     Subprocess A 
     Wet solids stream  20   a  from system  100   a  is pumped to solids-liquid extractor system  200   a  by piping. Examples of suitable equipment for system  200   a  have been provided previously as solids-liquid extractor system  200 , and a preferred system  200   a  includes three separators  216 . Typically solvent extraction system  200   a  operates in a counter-current arrangement. 
     Also entering solvent extraction system  200   a  is a second solvent, stream  70   a . In this embodiment, the solvent is n-propyl bromide. n-propyl bromide has a lower heat of vaporization or enthalpy of vaporization than the water in feed stream  10   a  and the ethanol of stream  15   a.    
     In solvent extraction system  200   a , ethanol in stream  20   a , particularly that in the interstitial spaces of the solids, is replaced with n-propyl bromide from stream  70   a . The ethanol leaves system  200   a  leave as stream  230   a  and the solids, now wet with n-propyl bromide exit system  200   a  as stream  220   a.    
     Stream  220   a  is fed to a dryer  300   a  where n-propyl bromide and any other remaining volatile liquids or solvents are removed from the solids. Dryer  300   a  is the only unit in subprocess A that uses thermal energy. Examples of suitable equipment for dryer  300   a  have been previously described in respect to dryer  300 . Dry solids exit as output stream  90   a . The thermally removed solvent exits dryer  300   a  as stream  80   a , a vapor. Stream  80   a  is combined with liquid stream  230   a . This combined stream  80   a / 230   a  and stream  30   a  is fed into liquid-liquid extraction unit  400   a  in ‘water-from-solvents’ separation subprocess B. 
     Subprocess B 
     Combined stream  30   a  is provided to the bottom of process unit  400   a . A solvent stream  80   a / 230   a  enters at the top of unit  400   a . In this embodiment, the solvent of stream  80   a / 230   a  is n-propyl bromide. Stream  30   a  has a density less than n-propyl bromide, which enters at the top of unit  400   a . Thus the components of stream  80   a / 230   a  fall in the column while components in stream  30   a  rise in the column. Normal-propyl bromide, with a density of 1.3, will therefore exit out the bottom of the column as a solvent-rich stream  65   a , and the water-rich phase will exit out the top as stream  45   a.    
     Stream  45   a  is high in alcohol and water content with other lesser water-soluble components. There may be a small amount of n-propyl bromide in stream  45   a.    
     Stream  45   a  is sent to process unit  500   a , an evaporation or distillation device. Unit  500   a  separates the ethanol from the mixture of stream  45   a ; the ethanol, as a vapor and as an azeotrope of ethanol and water, leaves unit  500   a  as stream  60   a . Stream  60   a  may either be condensed, used as is, or sent for further processing to remove other components. Stream  60   a  may also be conveyed, as a vapor, to other purification devices to provide a product ethanol that is 99.9+% pure. 
     Stream  55   a  from process unit  500   a  is mostly water with some water soluble components that did not vaporize in unit  500   a . This liquid stream  55   a  may be used as is or further refined or purified. 
     Returning to unit  400   a , stream  65   a , the high organic bottom stream from unit  400   a , is also sent to a distillation or evaporation device. The majority of stream  65   a  consists of n-propyl bromide and the remainder of stream  65   a  is composed of fat soluble components, such as corn oil. Stream  65   a  feeds process device  600   a  which has an exiting vapor stream  75   a  and a liquid stream  50   a . Stream  75   a  is primarily n-propyl bromide. This vapor can be condensed and recycled (reused) in the solid-liquid extraction subprocess A, as stream  70   a . The liquid stream  50   a  is primarily fats and oils; this stream may be used as is or may be further refined. 
     Alternate Embodiments of the Process 
     A first alternate embodiment of the process is diagrammatically illustrated in  FIG. 8 . This process has an initial extraction process that removes the water from the solids followed by two subprocesses. The first subprocess removes the initial solvent from the solids and a second subprocess that separates and reclaims the water, solvent and other components. The description of this preferred process uses the same reference numerals used before for like streams and equipment, as appropriate, except that the reference numerals are followed by a “b”. 
     In this embodiment, feed stream  10   b  is fed into a solid-liquid extraction system  100   b  where the solids of feed stream  10   b  are separated from the water. Examples of suitable solids-liquid extraction equipment have been described previously as water extraction system  100 , and a preferred system  100   b  includes separators  116 . 
     An extraction solvent stream  15   b  is fed into water extraction system  100   b  with feed stream  10   b . In this embodiment, the extraction solvent is ethanol. Ethanol has a lower heat of vaporization or enthalpy of vaporization than the water in feed stream  10   b . The resulting output streams from system  100   b  are wet solids stream  20   b  and liquid stream  30   b . Solid stream  20   b  progresses to and is treated by ‘solvent-from-solids’ separation subprocess A, described below. Liquid stream  30   b  progresses to and is treated by ‘water-from-solvents’ separation subprocess B, also described below. 
     Subprocess A 
     From water extraction system  100   b , solid stream  20   b  is conveyed to solid-liquid extraction system  200   b  where the solvent from stream  15   b  is removed from the solids and replaced with second solvent entering as stream  70   b . In this embodiment, the solvent is ethyl ether, which has a lower heat of vaporization or enthalpy of vaporization that the water in feed stream  10   b  and the ethanol of stream  15   b . The ethyl ether of stream  70   b  may be provided by an external source, but is preferably recycled from the solvent removed from the solids, and from overhead stream  75   b  from still  600   b , as will be discussed below. 
     In solvent extraction system  200   b , ethanol in stream  20   b  is replaced with ethyl ether from stream  70   b . The ethanol leaves system  200   b  as stream  230   b  and the solids, now wet with ethyl ether, exit system  200   b  as stream  220   b.    
     Stream  220   b  is fed to a dryer  300   b  where ethyl ether and any other remaining volatile liquids or solvents are removed from the solids. The thermally removed solvent exits dryer  300   b  as stream  80   b , a vapor, and progresses to condenser  800 . Depending on the volume of stream  80   b , a portion of it may be removed as an ether side-stream. The remainder of stream  80   b  is returned to system  200   b.    
     Stream  230   b  progresses to ‘water-from-solvents’ separation subprocess B. 
     Subprocess B 
     ‘Water-from-solvents’ separation subprocess B treats liquid stream  30   b  from water extraction system  100   b  and stream  230   b  from subprocess A. Stream  30   b  is provided to the top of process unit  400   b . Liquid-liquid extraction unit  400   b  is typically a tall column with four ports, one inlet at the top and one inlet at the bottom, and two outlets, one at the top and one at the bottom; streams from the two inlets run counter-current. A solvent stream  40   b  enters at the bottom of unit  400   b . In this embodiment, the solvent of stream  40   b  is ethyl ether. Thus the components of stream  40   b  rise in the column while components in stream  30   b  fall in unit  400   b , resulting in exiting aqueous bottom exit stream  45   b , which has a lower concentration of ethanol than stream  30   b  did at the inlet, having transferred some ethanol to the ether stream. Also exiting is top exit stream  65   b , mostly ether but which has a higher concentration of ethanol than stream  40   b  did at the inlet, having received some ethanol from stream  30   b.    
     Bottom exit stream  45   b  is composed of the water, ethanol, and some other hydrocarbons from feed stream  10   b , and a small amount of ethyl ether from stream  40   b . Stream  45   b  is fed into a still  500   b , where thermal energy is used to separate all volatile components from water and provide an overhead stream  60   b  and a bottoms stream  55   b . Still  500   b  is one of only two process elements, in this embodiment of subprocess B, that utilizes thermal energy. 
     Overhead stream  60   b  includes ethanol and any trace amount of ether that may have been present in stream  45   b . Bottom stream  55   b  includes water and any other heavy materials. A generally small amount of external heat or energy is needed to provide the separation, due to the different boiling points of water and solvents. 
     Overhead stream  60   b  progresses to a condenser  700 , where ethanol vapors are condensed to liquid. The resulting liquid stream is fairly pure, typically at least 90% and preferably at least 95%. The ethanol can be collected and used for solvent stream  15   b . Bottoms stream  55   b  is generally sufficiently pure water to allow disposal with a minimum of further purification. 
     Top exit stream  65   b  from liquid-liquid extraction unit  400   b  contains the majority of ether from unit  400   b , a major amount of ethanol from stream  30   b , and typically includes a small amount of water. Top exit stream  65   b  and stream  230   b  are fed into a still  600   b , the second of the two process elements of subprocess B in this embodiment that utilizes thermal energy. Top exit stream  65   b  is separated by still  600   b  into an overhead stream  75   b  and a bottoms stream  67 . 
     Overhead stream  75   b  includes the ether; typically this stream is fairly pure, typically at least 95% pure and preferably at least 98% pure. Overhead stream  75   b  is recycled into the process and combined with ether stream  80   b , out from dryer  300   b  of subprocess A. 
     Bottom stream  67  includes the heavier ethanol; this stream is fairly pure, typically at least 90% pure and preferably at least 95% pure. Bottom stream  67 , composed of fairly pure ethanol, can be treated in the same manner as stream  60   b , either collected, returned to the process as solvent stream  15   b , or further purified. 
     A second alternate embodiment of the process is diagrammatically illustrated in  FIG. 9 . This process has an initial extraction process that removes the water from the solids followed by two subprocesses. The first subprocess removes the initial solvent from the solids and a second subprocess that separates and reclaims the water, solvent and other components. The description of this preferred process uses the same reference numerals used before for like streams and equipment, as appropriate, except that the reference numerals are followed by a “c”. 
       FIG. 9  shows a process similar to the process of  FIG. 8 , except this embodiment includes additional process equipment. Bottom stream  67   c  from unit  600   c  is sent to an evaporator unit  900 , which is designed to boil off an azeotropic mixture of ethanol and water, to provide stream  76  and stream  77 . Stream  76  contains a mixture of ethanol, water preferably and some small amounts of additional volatile material. Stream  76  progresses to system  1000 , a series of molecular sieves. System  1000  takes the azeotropic mixture from evaporator unit  900  and provides ethanol, stream  78 . Remaining water from the separation leaves system  1000  as stream  79 . 
     The nonvolatilized portion of stream  75   c  exits unit  900  as stream  77 , relatively clean water. 
     A third alternate embodiment of the process is diagrammatically illustrated in  FIG. 10 . The description of this preferred process uses the same reference numerals used before for like streams and equipment, as appropriate, except that the reference numerals are followed by a “d”. 
       FIG. 10  is another embodiment of the process and is similar to the process of  FIG. 9 . However, the process of  FIG. 10  has an added liquid/liquid extractor unit  450 . Unlike the embodiments of  FIGS. 8 and 9 , the aqueous (bottom) stream  45   d , from unit  400   d  does not feed unit  500   d  directly, but instead is one of two feed streams to unit  450 . Similar to unit  400   d , unit  450  extracts ethanol from an aqueous feed stream using an ether, which is the other feed stream  46  provided to unit  450 . The organic (top) phase stream from unit  450 , stream  47  is combined with organic phase stream  65   d  from unit  400   d . Additionally, vapor stream  60   d  from unit  500   d  is not sent to a condenser but instead is combined with streams  47  and  65   d  and the resulting stream is combined with stream  230   d  from system  200   d . This combined stream is fed to unit  600   d . Also in this embodiment, stream  67   d  is split into streams  61  and  62 . Stream  62  carries the appropriate amount of ethanol to provide 200-proof ethanol and ethanol to regenerate the sieve beds of system  1000 . Stream  61  is sent to a storage tank for reuse in the process. 
     Alternate embodiments, of any of the process described above, which utilize an initial extraction process that removes the water from the solids followed by two subprocesses, are within the scope of this invention. 
     The various processes described above used two solvents to remove water from solids; specifically, the first solvent replaced the water, and then the second solvent replaced the first solvent. Although the description above labeled solvents as “first solvents” and “second solvents”, and the like, it should be recognized that these groupings are not limiting. In some designs, for example, a solvent listed in the “second solvent” group may be used as a first solvent; similarly, a solvent listed in the “first solvent” group may be used as a second solvent. The only basis is that the second solvent has a heat of vaporization, enthalpy of vaporization, or other such physical property, that is less than that of the first solvent. If a third solvent is used, the third solvent would have a heat of vaporization, enthalpy of vaporization, or other such physical property, that is less than that of the second solvent. 
     General Operating Conditions 
     The following generally operating conditions are suitable for the process according to the invention, when operated in a typical pilot plant scale. 
     
       
         
               
               
               
             
               
               
             
           
               
                   
                   
               
               
                   
                 Stream 
                 Flowrate 
               
               
                   
                   
               
             
             
               
                   
                 Feed stream 10 
                 100-120 lbs/min (15-25 gal/min) 
               
               
                   
                 First solvent stream 15 
                 Based on stream 10 
               
               
                   
                 Solids stream 20 
                 Based on streams 10 and 15, and 
               
               
                   
                   
                 on stream 70 
               
               
                   
                 Second solvent stream 70 
                 Based on stream 20 
               
               
                   
                   
               
             
          
           
               
                   
                 (I) 
               
               
                 
                   
                     
                       
                         
                           
                             First 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             solvent 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             stream 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             15 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 lb 
                                 / 
                                 min 
                               
                               ) 
                             
                           
                           
                             Feed 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Stream 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             10 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 lb 
                                 / 
                                 min 
                               
                               ) 
                             
                           
                         
                         = 
                         
                           about 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1.0 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           to 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           0.3 
                         
                       
                     
                   
                 
               
               
                   
                 (II) 
               
               
                 
                   
                     
                       
                         
                           
                             Second 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             solvent 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             stream 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             70 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 lb 
                                 / 
                                 min 
                               
                               ) 
                             
                           
                           
                             Solids 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Stream 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             20 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 lb 
                                 / 
                                 min 
                               
                               ) 
                             
                           
                         
                         = 
                         
                           about 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           1.1 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           to 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           0.3 
                         
                       
                     
                   
                 
               
               
                 Process temperature = 85-90° F. 
               
               
                 Process pressure = atmospheric 
               
             
          
         
       
     
     The flow rates within the system that are useful in accordance with the invention are indicated above. Generally, feed stream  10  has a flow rate of 100 to 120 lbs/min. The flow rate of first solvent stream  15  is set in accordance with equation (I). The flow rates of second solvent stream  70  generally range from 10-20 lbs/min, but may also be adjusted relative to stream  20  through equation (II). The flow rates of the various streams into and out from subprocess B are generally governed by stream flow rates in system  100  and subprocess A. 
     Exemplary Process Conditions 
     Provided below are exemplary stream components and proposed material flow rates for a commercial size, modeled process, described in reference to  FIG. 7 , which used n-propyl bromide as the second solvent. A binary diagram, for n-propyl bromide/ethanol/water is provided as  FIG. 11 . It was found that using n-propyl bromide, for a system desirous of separating water and ethanol, was beneficial in that there was a tendency for the system to equilibrate at a low water percentage. 
     
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Solids 
                 Ethanol 
               
               
                   
                 Feed Stream 
                 Feed Stream 
               
               
                   
                 10a 
                 15a 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Flow Rate 
                 4000 
                 lb/min 
                 1090 
                 lb/min 
               
             
          
           
               
                   
                 Fiber 
                 12 
                 wt-% 
                 0 
               
             
          
           
               
                   
                 Oil 
                 Trace 
                 0 
               
             
          
           
               
                   
                 Water 
                 73 
                 wt-% 
                 7.4 
                 wt-% 
               
             
          
           
               
                   
                 Glycerol 
                 Trace 
                 0 
               
               
                   
                 Acetic Acid 
                 Trace 
                 0 
               
             
          
           
               
                   
                 Ethanol 
                 13 
                 wt-% 
                 92.6 
                 wt-% 
               
               
                   
                   
               
             
          
         
       
     
     In unit  100   a , feed stream  10   a  (usually at a temperature of about 85-90° F.) and first solvent stream  15   a  would be sent through a series of six screen extractor units  116  (see  FIG. 2 , where a series of three screen extractor units  116 A,  161 B,  116 C are illustrated). The resulting streams from the six extractors would be: 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Flow Rate 
                 Water 
                 Ethanol 
                 Fiber 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Extractor #1 
                 3543 lb/min 
                 70 wt-% 
                 17 wt-% 
                 11 wt-% 
               
               
                 solids stream 
               
               
                 Extractor #2 
                 3216 lb/min 
                 65 wt-% 
                 21 wt-% 
                 12 wt-% 
               
               
                 solids stream 
               
               
                 Extractor #3 
                 2889 lb/min 
                 58 wt-% 
                 27 wt-% 
                 14 wt-% 
               
               
                 solids stream 
               
               
                 Extractor #4 
                 2562 lb/min 
                 50 wt-% 
                 33 wt-% 
                 15 wt-% 
               
               
                 solids stream 
               
               
                 Extractor #5 
                 2234 lb/min 
                 40 wt-% 
                 42 wt-% 
                 17 wt-% 
               
               
                 solids stream 
               
               
                 Extractor #6 
                 1906 lb/min 
                 26 wt-% 
                 53 wt-% 
                 20 wt-% 
               
               
                 solids stream 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Wet Solids 
                 Aqueous 
               
               
                   
                 Stream 
                 Stream 
               
               
                   
                 20a 
                 30a 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Flow Rate 
                 1906 
                 lb/min 
                 3251 
                 lb/min 
               
               
                   
                 Fiber 
                 20 
                 wt-% 
                 3 
                 wt-% 
               
             
          
           
               
                   
                 Oil 
                 Trace 
                 0 
               
             
          
           
               
                   
                 Water 
                 26 
                 wt-% 
                 78 
                 wt-% 
               
             
          
           
               
                   
                 Glycerol 
                 Trace 
                 0 
               
               
                   
                 Acetic Acid 
                 Trace 
                 0 
               
             
          
           
               
                   
                 Ethanol 
                 53 
                 wt-% 
                 19 
                 wt-% 
               
               
                   
                   
               
             
          
         
       
     
     Wet solids stream  20   a  would progress to unit  200   a , where it and second solvent stream  70   a  would be sent through a series of six screen extractor units  216  (see  FIG. 5 , where a series of three screen extractor units  216 A,  216 B,  216 C are illustrated). The resulting streams from the six extractors would be: 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Flow Rate 
                 Water 
                 Ethanol 
                 n-PB 
                 Fiber 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Extractor 
                 1799 lb/min 
                 23 wt-% 
                 49 wt-% 
                  6 wt-% 
                 22 wt-% 
               
               
                 #1 solids 
               
               
                 stream 
               
               
                 Extractor 
                 1691 lb/min 
                 21 wt-% 
                 44 wt-% 
                 12 wt-% 
                 23 wt-% 
               
               
                 #2 solids 
               
               
                 stream 
               
               
                 Extractor 
                 1583 lb/min 
                 18 wt-% 
                 38 wt-% 
                 20 wt-% 
                 25 wt-% 
               
               
                 #3 solids 
               
               
                 stream 
               
               
                 Extractor 
                 1475 lb/min 
                 14 wt-% 
                 31 wt-% 
                 29 wt-% 
                 26 wt-% 
               
               
                 #4 solids 
               
               
                 stream 
               
               
                 Extractor 
                 1368 lb/min 
                 10 wt-% 
                 23 wt-% 
                 38 wt-% 
                 28 wt-% 
               
               
                 #5 solids 
               
               
                 stream 
               
               
                 Extractor 
                 1260 lb/min 
                  6 wt-% 
                 13 wt-% 
                 50 wt-% 
                 31 wt-% 
               
               
                 #6 solids 
               
               
                 stream 
               
               
                   
               
             
          
         
       
     
     The miscella stream from Extractor # 1  would correspond to stream  230   a  of  FIG. 7 . The components of stream  230   a  are provided below. 
     The solid stream obtained from Extractor # 6  would correspond to stream  220   a  of  FIG. 7 . Stream  220   a , fed into dryer  300   a , provides solids stream  90   a  and vapor stream  80   a . Solids stream  90   a  would be a flow of 389 lb/min of 100% solids 
     
       
         
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Vapor 
                 Miscella 
                 Combined 
               
               
                   
                 stream 
                 stream 
                 stream 
               
               
                   
                 80a 
                 230a 
                 80a/230a 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Flow Rate 
                 871 
                 lb/min 
                 1410 
                 lb/min 
                 2281 
                 lb/min 
               
               
                 Water 
                 8 
                 wt-% 
                 30 
                 wt-% 
                 21 
                 wt-% 
               
               
                 Ethanol 
                 19 
                 wt-% 
                 62 
                 wt-% 
                 46 
                 wt-% 
               
               
                 n-PB 
                 72 
                 wt-% 
                 7 
                 wt-% 
                 32 
                 wt-% 
               
               
                   
               
             
          
         
       
     
     Combined stream  80   a / 230   a  would be fed into the top of separation column  400   a  and aqueous stream  30   a  would be fed into the bottom of column  400   a  and streams  45   a  and  65   a  would exit. In this example, no additional solvent, as stream  40   a , was added. 
     
       
         
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Aqueous 
               
               
                   
                 Top Organic 
                 Bottom 
               
               
                   
                 Stream 45a 
                 Stream 65a 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Flow Rate 
                 655 
                 lb/min 
                 4877 
                 lb/min 
               
               
                   
                 Water 
                 1 
                 wt-% 
                 61 
                 wt-% 
               
               
                   
                 Ethanol 
                 2 
                 wt-% 
                 34 
                 wt-% 
               
               
                   
                 n-PB 
                 93 
                 wt-% 
                 3 
                 wt-% 
               
               
                   
                 Oils 
                 4 
                 wt-% 
                 0 
                 wt-% 
               
               
                   
                 Fiber/solids 
                 0 
                 wt-% 
                 2 
                 wt-% 
               
               
                   
                   
               
             
          
         
       
     
     Stream  45   a  would be fed to still  500   a  and the exiting streams  60   a ,  55   a  would have the compositions listed below. In this example, a steam sparge stream, at 35 lb/min, was added to carry or otherwise facilitate transporting the solvents to the top of the still. Stream  65   a  would be fed to still  600   a  and the exiting streams  75   a ,  50   a  would have the compositions listed below. In this example, heat exchangers would be used for flashing steam  65   a  prior to entering still  600   a ; this would decrease the entering mass flow rate to about 4700 lb/min. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Vapor 
                 Oil Recovery 
                 Ethanol 
                 Water Stream 
               
               
                   
                 Stream 60a 
                 Stream 55a 
                 Recovery 75a 
                 50a 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Flow Rate 
                 665 
                 lb/min 
                 25 
                 lb/min 
                 1706 
                 lb/min 
                 3003 
                 lb/min 
               
               
                 Water 
                 6 
                 wt-% 
                 0.6 
                 wt-% 
                 6 
                 wt-% 
                 95 
                 wt-% 
               
               
                 Ethanol 
                 2 
                 wt-% 
                 0 
                 wt-% 
                 92 
                 wt-% 
                 0 
                 wt-% 
               
               
                 n-PB 
                 92 
                 wt-% 
                 0 
                 wt-% 
                 2 
                 wt-% 
                 0 
                 wt-% 
               
               
                 Oils/glycerine 
                 0 
                 wt-% 
                 99.3 
                 wt-% 
                 0 
                 wt-% 
                 2 
                 wt-% 
               
               
                 Fiber/solids 
                 0 
                 wt-% 
                 0 
                 wt-% 
                 0 
                 wt-% 
                 3 
                 wt-% 
               
               
                   
               
             
          
         
       
     
     Additional Exemplary Process Conditions 
     Provided below are exemplary stream components and proposed material flow rates for a modeled process described in reference to  FIG. 10 , which used ether as the second solvent. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Solids Feed 
                   
                 Ethanol Feed 
                   
               
               
                   
                 Stream 10 d 
                   
                 Stream 15 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 12.2 
                 398.2 
                 0 
                 0 
               
               
                   
                 Oil 
                 0.6 
                 19.6 
                 0 
                 0 
               
               
                   
                 Water 
                 69.9 
                 2281.5 
                 4.5 
                 88.1 
               
               
                   
                 Glycerol 
                 1.2 
                 39.2 
                 0 
                 0 
               
               
                   
                 Acetic Acid 
                 0.1 
                 3.3 
                 0 
                 0 
               
               
                   
                 Ethanol 
                 16.0 
                 522.2 
                 82.8 
                 1621.6 
               
               
                   
                 Ether 
                 0 
                 0 
                 12.7 
                 248.7 
               
               
                   
                 Total 
                 100 
                 3264 
                 100 
                 1958.4 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Wet Solids 
                   
                 Aqueous 
                   
               
               
                   
                 Stream 20 d 
                   
                 Stream 30 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 44.1 
                 394.2 
                 0.1 
                 4.0 
               
               
                   
                 Oil 
                 1.1 
                 9.8 
                 0.2 
                 9.8 
               
               
                   
                 Water 
                 10.6 
                 94.8 
                 52.6 
                 2274.9 
               
               
                   
                 Glycerol 
                 2.2 
                 19.6 
                 0.5 
                 19.6 
               
               
                   
                 Acetic Acid 
                 0 
                 0 
                 0.1 
                 3.2 
               
               
                   
                 Ethanol 
                 36.5 
                 326.4 
                 42.0 
                 1817.4 
               
               
                   
                 Ether 
                 5.6 
                 50.1 
                 4.6 
                 198.7 
               
               
                   
                 Total 
                 100 
                 894.9 
                 100 
                 4327.5 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Ether Feed 
                   
                 Ether Feed 
                   
               
               
                   
                 Stream 40 d 
                   
                 Stream 70 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Oil 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Water 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Glycerol 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Acetic Acid 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ethanol 
                 3.0 
                 120.5 
                 3.0 
                 26.8 
               
               
                   
                 Ether 
                 97.0 
                 3894.7 
                 97.0 
                 868.1 
               
               
                   
                 Total 
                 100 
                 4015.2 
                 100 
                 894.9 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Wet Solids 
                   
                 Liquid 
                   
               
               
                   
                 Stream 220 d 
                   
                 Stream 230 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 46.9 
                 390.3 
                 0.4 
                 3.9 
               
               
                   
                 Oil 
                 0.0 
                 0.2 
                 1.0 
                 9.6 
               
               
                   
                 Water 
                 5.7 
                 47.4 
                 4.9 
                 47.4 
               
               
                   
                 Glycerol 
                 0.0 
                 0.4 
                 2.0 
                 19.2 
               
               
                   
                 Acetic Acid 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                   
                 Ethanol 
                 0.4 
                 3.3 
                 36.5 
                 350.0 
               
               
                   
                 Ether 
                 46.9 
                 390.3 
                 55.1 
                 527.8 
               
               
                   
                 Total 
                 100 
                 831.8 
                 100 
                 958.0 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Dried Solids 
                   
                 Ether Solvent 
                   
               
               
                   
                 Stream 90 d 
                   
                 Stream 80 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 89.0 
                 390.3 
                 0 
                 0 
               
               
                   
                 Oil 
                 0 
                 0.2 
                 0 
                 0 
               
               
                   
                 Water 
                 10.8 
                 47.4 
                 0 
                 0 
               
               
                   
                 Glycerol 
                 0.1 
                 0.4 
                 0 
                 0 
               
               
                   
                 Acetic Acid 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ethanol 
                 0 
                 0 
                 0.8 
                 3.3 
               
               
                   
                 Ether 
                 0 
                 0.4 
                 99.2 
                 389.9 
               
               
                   
                 Total 
                 100 
                 438.7 
                 100.0 
                 393.2 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Bottoms 
                   
                 Top 
                   
               
               
                   
                 Stream 45 d 
                   
                 Stream 65 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 0 
                 0 
                 0.1 
                 4.0 
               
               
                   
                 Oil 
                 0 
                 0 
                 0.2 
                 9.8 
               
               
                   
                 Water 
                 79.5 
                 2274.9 
                 0 
                 0 
               
               
                   
                 Glycerol 
                 0.7 
                 19.6 
                 0 
                 0 
               
               
                   
                 Acetic Acid 
                 0.1 
                 3.2 
                 0 
                 0 
               
               
                   
                 Ethanol 
                 18.4 
                 527.0 
                 25.7 
                 1410.8 
               
               
                   
                 Ether 
                 1.2 
                 35.1 
                 74.0 
                 4058.3 
               
               
                   
                 Total 
                 100 
                 2859.8 
                 100 
                 5482.9 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Ethanol 
                   
                 Water 
                   
               
               
                   
                 Stream 60 d 
                   
                 Stream 55 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Oil 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Water 
                 5.0 
                 27.7 
                 99.0 
                 2247.1 
               
               
                   
                 Glycerol 
                 0 
                 0 
                 0.9 
                 19.6 
               
               
                   
                 Acetic Acid 
                 0 
                 0 
                 0.1 
                 3.2 
               
               
                   
                 Ethanol 
                 95.0 
                 527.0 
                 0 
                 0 
               
               
                   
                 Ether 
                 0.0 
                 0.0 
                 0 
                 0 
               
               
                   
                 Total 
                 100 
                 554.8 
                 100 
                 2270.0 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Ether Product 
                   
                 Ethanol 
                   
               
               
                   
                 Stream 75 d 
                   
                 Stream 67 d 
               
             
          
           
               
                   
                 Component 
                 wt-% 
                 lb/min 
                 wt-% 
                 lb/min 
               
               
                   
                   
               
             
          
           
               
                   
                 Fiber 
                 0 
                 0 
                 0.4 
                 7.9 
               
               
                   
                 Oil 
                 0 
                 0 
                 1.1 
                 19.4 
               
               
                   
                 Water 
                 0.1 
                 2.4 
                 2.5 
                 40.0 
               
               
                   
                 Glycerol 
                 0 
                 0 
                 1.1 
                 19.2 
               
               
                   
                 Acetic Acid 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ethanol 
                 1.0 
                 46.3 
                 94.9 
                 1714.5 
               
               
                   
                 Ether 
                 99.0 
                 4585.7 
                 0 
                 0.5 
               
               
                   
                 Total 
                 100 
                 4634.5 
                 100 
                 1806.4 
               
               
                   
                   
               
             
          
         
       
     
     Only three pieces of the process equipment from the system depicted in and described with reference to  FIG. 10  use thermal energy. Dryer  1300 , which is a Schnecken tube-type dryer, uses an exemplary 77.3 lb/min of steam, still  1700  uses an exemplary 6532 lb/min of steam, and water separator  1500  uses an exemplary 199.5 lb/min of steam. 
     The above specifications provide a complete description of the process, equipment, and compositions of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.