Abstract:
A method of increasing the yield of oil production in a process of producing bio-ethanol in particularly comprises: creating concentrated syrup as a by-product from an ethanol production, and recovering oil from the concentrated syrup, wherein the step of recovering oil from the concentrated syrup includes using a horizontal axis centrifuge, and wherein the step of using a horizontal axis centrifuge includes using a bowl, a discharge of deoiled syrup and a baffle plate, the baffle plate being located inside of the bowl and retaining oil from the discharge of deoiled syrup.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a method of and a device for increasing the yield of oil production in a process of producing bio-ethanol. 
         [0003]    2. Description of the Related Art 
         [0004]    In known bio-ethanol plants stillage of grains such as corn is processed in order to produce ethyl alcohol, or so called bio-ethanol. The process usually is a dry milling process in which the starch in the grains is fermented. The fermentation creates a by-product or waste product, the so called whole stillage. The whole stillage is separated into distillers wet grains and the so called thin stillage. The thin stillage contains oil and is usually evaporated to become concentrated syrup and added to the solid waste materials to be dried and used as a supplement animal feed. 
         [0005]    New efforts of improving this process are made by continuously pumping the concentrated syrup into a sedimentation tank and separating statically a part of the oil which is contained in the concentrated syrup. However, the yield of oil to be received in this new process is low. 
         [0006]    Accordingly, a need exists for a method of and a device for increasing the yield of recovering oil in a process of producing bio-ethanol. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with one aspect of the invention, a method of increasing the yield of oil production in a process of producing bio-ethanol is disclosed, the method comprising: creating concentrated syrup as a by-product from an ethanol production, and recovering oil from the concentrated syrup, wherein the step of recovering oil from the concentrated syrup includes using a horizontal axis centrifuge, i.e., a centrifuge having a horizontal axis, and wherein the step of using a horizontal axis centrifuge includes using a bowl or drum, a discharge of deoiled syrup and a baffle plate or congestion plate, the baffle plate being located inside of the bowl and retaining oil from the discharge of deoiled syrup. 
         [0008]    In accordance with another aspect of the invention, a device for increasing the yield of oil production in a process of producing bio-ethanol is disclosed, the device comprising: means for creating concentrated syrup as a by-product from an ethanol production, and means for recovering oil from the concentrated syrup, wherein said means for recovering oil from the concentrated syrup include a horizontal axis centrifuge, and wherein said horizontal axis centrifuge includes a bowl, a discharge of deoiled syrup and a baffle plate, the baffle plate being located inside of the bowl and retaining oil from the discharge of deoiled syrup. 
         [0009]    In accordance with still another aspect of the invention, a method of increasing the yield of oil production in a process of producing bio-ethanol is disclosed, the method comprising: creating concentrated syrup as a by-product from an ethanol production, and recovering oil from the concentrated syrup, wherein the step of recovering oil from the concentrated syrup includes using a horizontal axis centrifuge, and wherein the step of using a horizontal axis centrifuge includes using a discharge of oil at a bowl of the horizontal axis centrifuge, the discharge diameter of which is 0.90 to 1.10 times of the respective diameter of a discharge of deoiled syrup. 
         [0010]    In accordance with yet another aspect of the invention, a device for increasing the yield of oil production in a process of producing bio-ethanol is disclosed, the device comprising: means for creating concentrated syrup as a by-product from an ethanol production, and means for recovering oil from the concentrated syrup, wherein said means for recovering oil from the concentrated syrup include a horizontal axis centrifuge, and wherein said horizontal axis centrifuge includes a bowl, and a discharge of deoiled syrup and a discharge of oil at said bowl, the discharge diameter of said discharge of oil being 0.90 to 1.10 times of the respective diameter of said discharge of deoiled syrup. 
         [0011]    In accordance with still a further aspect of the invention, a method of increasing the yield of oil production in a process of producing bio-ethanol is provided, the method comprising: creating concentrated syrup as a by-product from an ethanol production, and recovering oil from the concentrated syrup, wherein the step of recovering oil from the concentrated syrup includes using a horizontal axis centrifuge, and wherein the step of using a horizontal axis centrifuge includes using a three-phase horizontal axis centrifuge. 
         [0012]    In accordance with yet another aspect of the invention, a device for increasing the yield of oil production in a process of producing bio-ethanol is disclosed, the device comprising: means for creating concentrated syrup as a by-product from an ethanol production, and means for recovering oil from the concentrated syrup, wherein said means for recovering oil from the concentrated syrup include a horizontal axis centrifuge, and wherein said horizontal axis centrifuge is a three-phase horizontal axis centrifuge. 
         [0013]    Preferably the step of using a baffle plate inside of a bowl of the horizontal axis centrifuge includes using a baffle plate, the diameter of which is 0.70 to 0.95 times of the respective diameter of the bowl of the horizontal axis centrifuge. 
         [0014]    In a preferred embodiment, the step of using a horizontal axis centrifuge includes discharging the recovered oil from the horizontal axis centrifuge by using an adjustable weir disk. 
         [0015]    In another preferred embodiment, the step of using a horizontal axis centrifuge includes discharging the recovered oil from the horizontal axis centrifuge by using an impeller disk or peeling disk. 
         [0016]    Further preferred, the step of creating concentrated syrup as a by-product from an ethanol production includes producing whole stillage, recovering thin stillage from the whole syrup by using a horizontal axis centrifuge and concentrating the thin stillage by using an evaporator. 
         [0017]    In a further preferred embodiment, the step of recovering oil from the concentrated syrup includes storing the concentrated syrup in a storage tank before conducting it to the horizontal axis centrifuge. 
         [0018]    The step of conducting the concentrated syrup from the storage tank to the horizontal axis centrifuge further preferably includes drawing off the concentrated syrup at the top of the syrup stored in the storage tank. 
         [0019]    Finally, in a further preferred embodiment the step of using a horizontal axis centrifuge includes providing a centrifugal acceleration of 1800 to 2100×G, preferably 1900 to 2000×G, most preferred 1960×G on the concentrated syrup in the horizontal axis centrifuge. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a schematic flow chart illustrating the process of producing bio-ethanol and creating whole stillage as a by-product of said production of bio-ethanol. 
           [0021]      FIG. 2  is a schematic flow chart illustrating the processing of the whole stillage of the bio-ethanol production of  FIG. 1  according to the prior art. 
           [0022]      FIG. 3  is a schematic flow chart illustrating the processing of the whole stillage of the bio-ethanol production of  FIG. 1  according to the invention, in order to increase the yield of oil production in the production of bio-ethanol. 
           [0023]      FIG. 4  is a longitudinal sectional view of a first embodiment of a device for increasing the yield of oil production in the process of producing bio-ethanol according to the invention. 
           [0024]      FIG. 5  is a longitudinal sectional view of a device similar to  FIG. 4  modified according to the invention. 
           [0025]      FIG. 6  is a longitudinal sectional view of a second embodiment of a device for increasing the yield of oil production in the process of producing bio-ethanol according to the invention. 
           [0026]      FIG. 7  is a longitudinal sectional view of a device similar to  FIG. 6  modified according to the invention. 
           [0027]      FIG. 8  is a longitudinal sectional view of a third embodiment of a device for increasing the yield of oil production in the process of producing bio-ethanol according to the invention. 
           [0028]      FIG. 9  is a longitudinal sectional view of a device similar to  FIG. 8  modified according to the invention. 
           [0029]      FIG. 10  is a longitudinal sectional view of a forth embodiment of a device for increasing the yield of oil production in the process of producing bio-ethanol according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    In  FIG. 1  a method  10  of producing bio-ethanol is shown. In a first step of this method  10 , grain  12  such as corn, is provided and milled in a step  14 . After said milling, water  16  and enzymes  18  are added. By heating of the mixture a liquefaction of starch is started and the enzymes provide a decomposition of starch into sugar in a step  20 . A further fermentation takes place in a step  22  converting the sugar into ethanol. 
         [0031]    The step  22  is followed by a distillation step  24  in which bio-ethanol  26  is received. The by-product of the distillation step  24 , a so called whole stillage  27 , is further separated mechanically in a step  28  via a horizontal axis centrifuge, preferable a two-phase helical conveyor centrifuge. In said step  28  the whole stillage  27  is separated into a solid phase, the so called distillers wet grains  30 , and a liquid phase, the so called thin stillage  32 . 
         [0032]    In  FIG. 2  the further processing of the distillers wet grains  30  and the thin stillage  32  according to the prior art is depicted. The thin stillage  32  is conducted to an evaporation step  34  in which water  36  is removed from a so called syrup  38 . The syrup  38  is added to the distillers wet grains  30  and dried in a step  40  in order to receive so called distillers dried grains with solubles  42 . The distillers dried grains with solubles  42  is used as a supplement animal feed. 
         [0033]    In  FIG. 3  the further processing of the thin stillage  32  according to the invention is depicted. The process according to the invention differs from the one of  FIG. 2  in that the syrup  38  is conducted to a sedimentation or storage tank  44  and further to a horizontal axis centrifuge  46 . The line for conducting the syrup  38  from the storage tank  44  to the horizontal axis centrifuge  46  is advantageously connected to the storage tank  44  above the feed of the storage tank  44 . Alternatively, the line is connected to the bottom of the storage tank  44 . Further preferred, the syrup  38  is conducted directly to the horizontal axis centrifuge  46 . The horizontal axis centrifuge  46  is especially adapted to recover a large amount of oil  48  out of the syrup  38  for improving the yield of recovering oil in said process  10  of producing bio-ethanol  26 . 
         [0034]    The rest of the syrup  38 , a so called deoiled syrup  50 , is conducted to the above mentioned step  40  in which it is dried, in order to become distillers dried grains with solubles  42 . 
         [0035]      FIG. 4  shows a first embodiment of a horizontal axis centrifuge  46  which is used in the process of  FIG. 3  for recovering oil  48  from the concentrated syrup  38 . The horizontal axis centrifuge  46  includes a horizontal rotation axis  52  and two bearings  54  and  56  on which a bowl or bowl  58  having a rotatable screw  60  therein is supported rotationally with respect to the axis  52 . The horizontal axis centrifuge  46  provides a centrifugal acceleration of 1800 to 2100×G, preferably 1900 to 2000×G, most preferred 1960×G on syrup  38 , which is located in the horizontal axis centrifuge  46 . 
         [0036]    The bowl  58  is provided with a first outlet  62  for a “liquid phase” and a second outlet  64  for a “solid phase”. The first outlet  62  is provided with an adjustable weir disk or plate  66  at one of the front walls of the bowl  58 , and the second outlet  64  is provided at the opposite front wall of the bowl  58  at a conical part  58   a  thereof. The conical part  58   a  forms nearly one half of the outer wall of the bowl  58 . The screw  60  serves as a transportation means in order to discharge material from a cylindrical part  58   b  of the bowl  58  radial inwardly along the conical part  58   a  and out of the second outlet  64 . 
         [0037]    The syrup  38  to be separated in the horizontal axis centrifuge  46  is conducted into the bowl  58  through an inlet  68  in the centre of the screw  60 . The recovered oil  48  is discharged via the first outlet  62  across the adjustable weir disk  66 , which may be adjusted even during rotation of bowl  58  and screw  60 . The deoiled syrup  50  is discharged via the screw  60  along said conical part  58   a  through the second outlet  64 . 
         [0038]    In order to further improve the process of discharging the deoiled syrup  50  relative to the recovered oil  48 , a modified horizontal axis centrifuge  46  is depicted in  FIG. 5 , which is similar to the one of  FIG. 4  except of a baffle plate  68  being located in one of the windings of screw  60  at the transition of the cylindrical part  58   b  to the conical part  58   a  of the bowl  58 . The baffle plate  68  serves to retain oil  48  from the second outlet  64 , said oil  48  floating on the syrup  38  in the radial inner part of bowl  58 . The baffle plate  68  is located at the screw  60  alternatively at the transition between the cylindrical part and the conical part of its windings. The baffle plate  68  begins at the hub of the screw  60  and is directed radial outwardly. It should be directed approximately lengthwise, i.e., in one of the planes in which the horizontal rotation axis  52  is located (see  FIG. 5 ). Alternatively, the baffle plate  68  may be directed orthogonal to the horizontal rotation axis  52 . 
         [0039]    The baffle plate  68  further helps to transport the deoiled syrup to the second discharge  64 . The deoiled syrup is very soft or pasty. Thus, the deoiled syrup is transported as a “heavy phase” via an accumulation at the baffle plate  68 . In other words, the deoiled syrup is pressed under the baffle plate  68  and up the conical part  58   a . In order to improve said transport of deoiled syrup, the diameter of the baffle plate  68  is 0.70 to 0.95 times of the respective diameter of the bowl  58 . 
         [0040]    In  FIG. 6  a second embodiment of a horizontal axis centrifuge  46  for recovering oil  48  from the concentrated syrup  38  according to the process of  FIG. 3  is shown. The horizontal axis centrifuge  46  of  FIG. 6  also includes a horizontal rotation axis  52  and two bearings  54  and  56  on which a rotatable drum or bowl  58  having a rotatable screw  60  therein is supported. The bowl  58  is again provided with a first outlet  62  for a “liquid phase” and a second outlet  64  for a “solid phase”. The first outlet  62  is provided with an impeller disk  70  at a front wall of the bowl  58  which is opposite of a conical part  58   a.    
         [0041]    The syrup  38  to be separated in the horizontal axis centrifuge  46  is again conducted into the bowl  58  through an inlet  68 . The recovered oil  48  is discharged under pressure via the first outlet  62  through the impeller disk  70 , which may be adjusted even during rotation of bowl  58  and screw  60 . The deoiled syrup  50  is again discharged via the screw  60  along said conical part  58   a  through the second outlet  64 . For improvement of the process of discharging the deoiled syrup  50  relative to the recovered oil  48 ,  FIG. 7  shows a modified horizontal axis centrifuge  46  in which a radial directed baffle plate  68  is located in one of the windings of screw  60  at the transition of the cylindrical part  58   b  of the bowl  58  and conical part  58   a.    
         [0042]      FIG. 8  shows a third embodiment of a horizontal axis centrifuge  46  for the recovering of oil  48  according to the process of  FIG. 3 . The horizontal axis centrifuge  46  of  FIG. 8  is a three-phase horizontal axis centrifuge also including a horizontal rotation axis  52  and two bearings  54  and  56  on which a rotatable drum or bowl  58  and a rotatable screw  60  are supported. The bowl  58  is provided with a first outlet  62  for a “first liquid phase”, a second outlet  64  for a “solid phase”, and a third outlet  72  for a “second liquid phase”. 
         [0043]    The syrup  38  to be separated in the horizontal axis centrifuge  46  is again conducted into the bowl  58  through an inlet  68 . 
         [0044]    The first outlet  62  is provided with an adjustable weir disk  66  and serves for discharging recovered oil  48 . 
         [0045]    The second outlet  64  is usually not used for discharging any material during the process of separating syrup  38 . In contrast, the second outlet  64  serves for finally emptying the bowl  58  after the end of operation of the horizontal axis centrifuge  46 . The screw  60  helps to spread the syrup  38  into the bowl  58  during the process of separation and to discharge residual material through the second outlet  64  at the end of the process. 
         [0046]    The deoiled syrup  50  is discharged under pressure via the third outlet  72 , which is provided with an adjustable impeller disk  70 . 
         [0047]    Alternatively, the second outlet  64  may serve for additionally discharging deoiled syrup  50  out of the bowl  58 . Therefore, the deoiled syrup  50  is discharged via the screw  60  along the conical part  58   a.    
         [0048]    For further improving the process of discharging the deoiled syrup  50  through the second outlet  64  relative to the recovered oil  48 ,  FIG. 9  shows a modified three-phase horizontal axis centrifuge  46  in which a radial directed baffle plate  68  is located in one of the windings of screw  60  at the transition of the cylindrical part  58   b  and conical part  58   a  of the bowl  58 . The first outlet  62  thereby forms a discharge of oil the discharge diameter of which being 0.90 to 1.10 times of the respective diameter of a corresponding discharge of deoiled syrup. 
         [0049]    In  FIG. 10  a fourth embodiment of a horizontal axis centrifuge  46  for the recovering of oil  48  according to the process of  FIG. 3  is depicted. The horizontal axis centrifuge  46  of  FIG. 10  is a two-phase horizontal axis centrifuge including a horizontal rotation axis  52  around which a rotatable drum or bowl  58  is located. The bowl  58  is provided with a first outlet  62  and a second outlet  64 , both provided at one side wall of the bowl  58 . Alternatively, the second outlet  64  may be provided at a side wall opposite to the one of the first outlet  62 . 
         [0050]    The syrup  38  to be separated in the horizontal axis centrifuge  46  of  FIG. 10  is again conducted into the bowl  58  through an inlet  68 . 
         [0051]    The first outlet  62  is provided with an adjustable weir disk  66  and serves for discharging recovered oil  48 . 
         [0052]    The second outlet  64  includes an adjustable impeller disk  70  and serves for discharging deoiled syrup  50  under pressure. 
         [0053]    Further, at the horizontal axis centrifuge  46  of  FIG. 10  (non-depicted) means for finally cleaning and removing residual material out of the bowl  58  may be provided.