Patent Application
20150284754
The present disclosure generally relates to biofuel production and, more specifically, to methods and apparatus for use in carrying out liquefaction of biomass slurries as a precursor to, for example, biofuel production (e.g., ethanol production, etc.).
This section provides background information related to the present disclosure which is not necessarily prior art.
Lignocellulosic materials, such as wood, herbaceous material, agricultural residues, corn fiber, waste paper, pulp and paper mill residues, etc. as well as municipal solid waste can be used to produce biofuels. And typically, production of biofuels from such lignocellulosic material includes pretreatment (e.g., physical, chemical, etc.) of the lignocellulosic material to form a biomass slurry, liquefaction of the resulting biomass slurry, saccharification and fermentation of the liquefaction slurry, and then biofuel recovery (e.g., via distillation, etc.).
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Example embodiments of the present disclosure generally relate to methods for carrying out liquefaction of slurries, for example, in liquefaction reactors, etc. using enzymes (e.g., cellulase, etc.). The liquefaction reactors may include alternating plug flow and continuously-stirred regions. In one example embodiment, a method for carrying out liquefaction of a biomass slurry generally includes measuring pH of the biomass slurry in multiple regions of a reactor; after each operation of measuring pH of the biomass slurry, adjusting the pH of the biomass slurry in the reactor as needed to a value within a desired range (e.g., between about 4 and about 6.5, etc.); and adding enzymes (e.g., cellulase enzymes, etc.) to the biomass slurry in the reactor. In some aspects of this example method, the enzymes are added to the biomass slurry in the reactor after at least two iterations of the operations of measuring pH of the biomass slurry and adjusting the pH of the biomass slurry as needed to a value within the desired range. In some aspects of this example method, the pH is measured in at least one plug flow region of the reactor. In some aspects of this example method, the pH is measured in at least one continuously-stirred region of the reactor. And, in some aspects of this example method, the pH is measured in multiple plug flow regions of the reactor.
In another example embodiment, a method for carrying out liquefaction of a pre-treated biomass slurry in a liquefaction reactor generally includes measuring an initial pH of the pre-treated biomass slurry (e.g., before the biomass slurry enters the reactor, etc.), and adjusting the initial pH of the biomass slurry as needed to a value within a desired range (e.g., between about 4 and about 6.5, between about 5.5 and about 6.5, etc.); adding enzymes (e.g., cellulase enzymes, etc.) to the pre-treated biomass slurry after adjusting the initial pH of the slurry to the value within the desired range; in a plug flow region of the liquefaction reactor, again measuring pH of the biomass slurry; and adjusting the pH of the biomass slurry measured in the plug flow region as needed to a value within the desired range.
Example embodiments of the present disclosure also generally relate to reactors for use in carrying out liquefaction of slurries. In one example embodiment, a tower reactor for use in carrying out liquefaction of a pre-treated biomass slurry generally includes alternating plug flow regions and continuously-stirred regions, agitators for moving the pre-treated biomass slurry in the continuously-stirred regions, probes positioned in multiple plug flow regions and configured to measure pH of the pre-treated biomass slurry in the multiple plug flow regions, first fluid lines positioned in communication with multiple ones of the continuously-stirred regions and configured to deliver an acid and/or a base to the pre-treated biomass slurry in the multiple ones of the continuously-stirred regions, and second fluid lines positioned in communication with multiple ones of the continuously-stirred regions and configured to deliver enzymes to the pre-treated biomass slurry in the multiple ones of the continuously-stirred regions.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
The liquefaction process of the illustrated method 100 is an enzymatic liquefaction process that utilizes enzymes to catalyze cellulolysis in the biomass slurry. In the illustrated method 100, cellulase enzymes are added to the biomass slurry to promote hydrolysis of cellulose in the biomass slurry (and conversion of the cellulose to glucose). With that said, it should be appreciated that suitable cellulase enzymes can be used in connection with the method 100 including, for example, enzymes from fungi, bacteria, protozoans, etc.; genetically engineered enzymes; etc. In other example embodiments, methods for carrying out liquefaction of biomass slurries may utilize enzymes other than cellulase enzymes, for example, enzyme cocktails, etc.
The cellulase enzymes used in the liquefaction process of the illustrated method 100 are pH sensitive and, for example, can significantly lose activity at pH values above about 6.5 or below about 4. As such, the illustrated method 100 is performed in connection with a series of multiple alternating plug flow and continuously-stirred regions (e.g., zones, containers, tanks, etc.). This allows for monitoring and/or controlling the pH of the biomass slurry throughout the series of plug flow and continuously-stirred regions (e.g., within each individual region, etc.). And in turn, the pH of the biomass slurry can be maintained within a desired range, for example, between about 4 and about 6.5, etc. throughout the liquefaction process to help promote efficient liquefaction (and cellulolysis) of the biomass slurry and help avoid denaturing of the cellulase enzymes. In one example embodiment, the cellulase enzymes used in the liquefaction process may have peak activity at a pH of about 5. As such, in this example embodiment, the pH of the biomass slurry may be maintained within a range of about 4.5 to about 5.5 (e.g., to retain greater than about ninety percent of the activity of the cellulase enzymes, etc.). In another example embodiment, different enzymes (e.g., enzymes other than cellulase enzymes, different types of cellulase enzymes, etc.) may be added to the biomass slurry at different locations in the liquefaction process as desired.
In the liquefaction process of the illustrated method 100, the continuously-stirred regions can make use of any suitable features (e.g., mechanical agitators, pumps, gravity, fluid recycle streams, other mixing means, etc.) to move, mix, stir, etc. the biomass slurry therein. What's more, in some example embodiments, the plug flow and continuously-stirred regions can be separate individual units arranged in series, while in other example embodiments they can all be located in series within a common reactor (e.g., a liquefaction reactor, a tower reactor, etc.), etc. Further, in some example embodiments, the plug flow and continuously-stirred regions can be oriented vertically (e.g., in towers, etc.), horizontally (e.g., with pumps, etc. moving the biomass slurry from one region to the next region, etc.), etc.
As shown in
The illustrated method 100 also includes adjusting the pH of the biomass slurry, if needed, to a value within the desired range (or to a specific desired value, etc.) after each operation of measuring the pH (as indicated generally at reference number 104 in
The illustrated method 100 further includes adding cellulase enzymes to the biomass slurry at one or more regions (e.g., at one or more different plug flow regions, at one or more different continuously-stirred regions, etc.) through the liquefaction process. The cellulase enzymes may be added in conjunction with adjusting the pH of the biomass so that, for example, the cellulase enzymes are added to the biomass at one or more regions when the pH of the biomass slurry in those regions is within the desired range (as indicated generally at reference number 106 in
In some aspects, the method 100 may also include measuring an initial pH of the biomass slurry before the biomass slurry enters, begins, etc. the liquefaction process. In these aspects, the method 100 may also include (although not required) adjusting the pH of the biomass slurry before it enters the liquefaction process, as needed, to a value within the desired range. And, the method 100 may then further include adding cellulase enzymes to the biomass slurry, again before the biomass slurry enters the liquefaction process (e.g., to initially reduce viscosity of the biomass slurry before it enters the liquefaction process to help improve mixing and thorough blending of the biomass slurry, pH control, enzyme activity, etc. during the liquefaction process, etc.). Here, it may also be desired to add a predetermined total amount of cellulase enzymes to the biomass slurry, taking into account the enzymes added before the biomass slurry enters the liquefaction process and the enzymes added during the liquefaction process. As such, a first portion of the predetermined total amount of enzymes (e.g., about sixty percent or less of the predetermined total amount of enzymes, etc.) may be added to the biomass slurry before it enters the liquefaction process, and then the remaining portion of the predetermined total amount of enzymes may be added to the biomass slurry during the liquefaction process (e.g., in one or more doses, etc.).
With continued reference to
Further, the illustrated method 100 includes measuring viscosity of the biomass slurry during the liquefaction process (e.g., in at least one of the plug flow regions and/or the continuously-stirred regions, etc.) (as indicated generally at reference number 110 in
It should be appreciated that at least one or more of the operations of the illustrated method 100 may be performed automatically (e.g., via automated processes, etc.). As such, these at least one or more of the operations may be monitored and/or controlled remotely (e.g., at locations away from the liquefaction process, etc.).
In addition, in some example embodiments, methods for carrying out liquefaction of biomass slurries may include fewer operations than illustrated in
In the illustrated operation 220, a pH of the biomass slurry is measured (as generally indicated at reference numbers 226a-d) in each of the four middle plug flow regions 222b-e to determine if the pH needs to be adjusted. If the measured pH is acceptable (e.g., within a desired range, for example, between about 4 and about 6.5, etc.; etc.), no further action is required. However, if the measured pH is not acceptable (e.g., outside the desired range, etc.), acid and/or base is added to the biomass slurry (as generally indicated at reference numbers 228a-e) to adjust the pH to an acceptable value (e.g., a value within the desired range, etc.). The illustrated operation 220 allows for adding acid and/or base to the biomass slurry in any one of the five continuously-stirred regions 224a-f and/or four middle plug flow regions 222b-e (as indicated by lines 230), when needed. As such, in some aspects of the operation 220, the acid and/or base can be added to the biomass slurry in the continuously-stirred region 224b-f immediately following the plug flow region 222b-e in which the corresponding pH measurement was taken.
The illustrated operation 220 also allows for adding enzymes (e.g., cellulase enzymes, different types of enzymes, etc.) to the biomass slurry in any one of the continuously-stirred regions 224a-f (as generally indicated at reference numbers 232a-e). As such, enzymes can be added as desired to any one or to multiple ones of the continuously-stirred regions 224a-f. As previously described, this may be done in conjunction with adjusting the pH of the biomass slurry so that, when adjusted, the pH is substantially optimized (e.g., within the desired pH range for the enzymes, etc.) to support the desired enzyme reactions (e.g., the cellulose hydrolysis, etc.). However, it should be appreciated that adding enzymes to any one or to multiple ones of the continuously-stirred regions 222a-f may alternatively be done, in one or more of the continuously-stirred regions 222a-f, independent of adjusting the pH of the biomass slurry in those regions.
In some aspects (and while not illustrated), the operation 220 may include measuring residence time of the biomass slurry in the plug flow regions 222a-f and/or continuously-stirred regions 224a-e, and/or may also include measuring viscosity of the biomass slurry during the liquefaction process, for example, in multiple ones of the plug flow regions 222a-f. This can help in monitoring progression, and effectiveness, of the liquefaction process.
With that said, in this embodiment, however, an initial pH of the biomass slurry is measured (as indicated generally at reference number 326f) before the biomass slurry enters (e.g., is pumped to, etc.) a first plug flow region 322a. In addition, the pH of the biomass slurry is also adjusted as needed (as indicated generally at reference number 328f) to fall within a desired range (e.g., between about 4 and about 6.5, etc.), and enzymes (e.g., cellulase enzymes, etc.) are then added to the biomass slurry (as indicated generally at reference number 332f) also before the biomass slurry enters the first plug flow region 322a. A pH of the biomass slurry can then be measured (as indicated generally at reference number 326g) in the first plug flow region 322a, with pH adjustment (as indicated generally at reference number 328a) and enzyme addition (as indicated generally at reference number 332a) following in a first continuously-stirred region 324a (with these operations then repeated as desired in the following plug flow and continuously-stirred regions 322b-e and 324b-e, for example, as described in connection with the operation 220 illustrated in
Further in this embodiment, a portion of the total enzymes (e.g., about sixty percent or less, etc.) to be added to the biomass slurry as part of the operation 320 is added before the biomass slurry enters the first plug flow region 322a. The remaining portions of the enzymes are then added to the biomass slurry at one or more different ones of the subsequent continuously-stirred regions 324a-e (as indicated at reference numbers 232a-e).
In the illustrated embodiment, each of the continuously-stirred regions 424a-e of the reactor 440 includes an agitator 442 (e.g., a blade arrangement, etc.) configured to move (e.g., mix, etc.) the biomass slurry within a corresponding continuously-stirred region 424a-e of the reactor 440. Each agitator 442 is coupled along a common drive shaft 444 that extends through the reactor 440. And, a motor 446 is provided to rotate the drive shaft 444. As such, rotation of the common drive shaft 444 rotates each of the agitators 442, in turn moving (e.g., mixing, etc.) the biomass slurry in the corresponding continuously-stirred regions 424a-e. In other example embodiments, movement (e.g., mixing, etc.) of the biomass slurry may be achieved using individual agitators in each of the continuously-stirred regions, pumps, jets, recirculation streams, etc.
Also in the illustrated embodiment, each of the plug flow regions 422a-f includes a probe 448 configured to measure a pH of the biomass slurry in the corresponding plug flow region 422a-f. And, fluid lines 450 are located in each of the continuously-stirred regions 424a-e to deliver an acid and/or a base to the biomass slurry, as needed. As such, following measurement of the pH of the biomass slurry in each of the plug flow regions 422a-e, acid and/or base can be delivered to the biomass slurry in the following continuously-stirred region 424a-e, if needed, via the fluid lines 450.
Further in the illustrated embodiment, fluid lines 452 are located in each of the continuously-stirred regions 424a-e to deliver enzymes (e.g., cellulase enzymes, etc.) to the biomass slurry. Again, this can be done in conjunction with adjusting the pH of the biomass slurry so that the pH is substantially optimized through the reactor 440 to support the desired enzyme reactions (e.g., the cellulose hydrolysis, etc.). Or, alternatively, adding enzymes to the continuously-stirred regions 422a-e may be done, in one or more of the continuously-stirred regions 422a-e, independent of adjusting the pH of the biomass slurry in those regions.
In the illustrated operation 560, the biomass is initially pretreated 562 using physical and/or chemical processes to form a biomass slurry (e.g., to liberate cellulose from the lignocellulosic material, etc.). Next, the pre-treated biomass slurry is subject to the liquefaction process 520 (e.g., hydrolysis of the liberated cellulose, etc.). Following the liquefaction process 520, the slurry is subject to an enzyme hydrolysis process 564, followed by a saccharification and fermentation process 566 (e.g., a separate saccharification process and a separate fermentation process, a simultaneous saccharification and fermentation (SSF) process, etc.). And then, a distillation process 568 is used to ultimately yield the biofuel.
Example embodiments are provided herein so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application claims the benefit of, and priority to, U.S. Provisional Application No. 61/716,949, filed Oct. 22, 2012, the entire disclosure of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US13/65559 | 10/18/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61716949 | Oct 2012 | US |
