Biomass treatment process and system

The present invention provides processes and systems for treating biomass and, e.g., making biofuels, such as bioethanol, from the biomass. More particularly, one process according to the present invention includes (a) inducing at least a first portion of a composition containing biomass and a working fluid to flow into a passage of a fluid processing apparatus, (b) injecting a high velocity transport fluid into the composition through a nozzle communicating with the passage of the fluid processing apparatus, whereby the transport fluid applies a shear force to the composition such that the working fluid is atomized and a vapor and droplet flow regime is formed downstream of the nozzle, (c) condensing the vapor and droplet flow regime, (d) transferring the composition to a first holding vessel, and (e) holding the composition in the first holding vessel at a first predetermined temperature for a first predetermined period of time, wherein a liquefaction enzyme is added to the composition prior to or during the process. Thereafter, the composition may be further processed to form a biofuel, such as, e.g., bioethanol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §120 of international application no. PCT/GB2008/050210, filed Mar. 21, 2008 and international application no. PCT/GB2008/050319, filed May 2, 2008. The contents of both international applications are hereby incorporated by reference as if recited in full herein.

FIELD OF THE INVENTION

The present invention provides, inter alia, a biomass treatment process and system suitable for use in the production of biofuels, including, e.g., bioethanol. More specifically, the present invention provides a single process and system for the conversion of both starch and cellulose present in a biomass composition into alcohol.

BACKGROUND OF THE INVENTION

The conversion of biomass into biofuel has taken on great significance in recent years as consumers and producers alike recognise the environmental and sustainability issues surrounding existing fossil fuels. The bulk of existing biofuel is derived from the fermentation of sugar crops and crops having high starch content, which will hereinafter be referred to as the “first generation” process. First generation processes typically involve an initial hydration step of mixing ground starch-based feedstock with water to form a slurry. The water may be pre-heated prior to being mixed with the feedstock. The slurry may additionally be heated in a vessel in order to activate the starch, and is then heated again and mixed with a liquefaction enzyme in order to convert the starch to long chain sugars. The activation stage typically uses steam-jacketed tanks or steam sparge heating to heat the slurry to the desired temperature. At the same time, agitation mixers, slurry recirculation loops, or a combination of the two mix the slurry. However, despite the presence of the recirculation pumps these heating methods can result in regions being created in the slurry tank or vessel whose temperature is much greater than the remainder of the tank. In such processes, starch hydrated early in the process can be damaged, e.g., denatured, if it comes into contact with these high temperature regions, resulting in a lower yield. These arrangements also do not provide particularly efficient mixing, as evidenced by the heat damage problem discussed above and also poor hydration of the starch.

These first generation processes normally use separate vessels for the activation and conversion stages of the process. Transfer of the slurry from the activation vessel to the conversion stage vessel is normally accomplished using centrifugal pumps, which impart a high shear force on the slurry and cause further damage to the hydrated starch as a result.

The conversion stage may also use steam- or water-jacketed tanks, or tanks heated by sparge heaters, to raise the temperature of the slurry to the appropriate level for the optimum performance of the liquefaction enzyme. Alternatively, jet cookers are employed to heat the incoming slurry into the conversion stage vessel. Not only can the slurry suffer the same heat damage as in the activation stage, but the high temperature regions also contribute to limiting the glucose yield from the process. The excessive heat of these regions promotes Maillard reactions, where the sugar molecules are destroyed due to interaction with proteins also present in the slurry. The combination of these Maillard losses with the shear losses from the transfer pumps limits the glucose yield available. Additionally, existing liquefaction processes require a long residence time for the slurry in the conversion stage to ensure that as much starch is converted to sugar as possible. This has a negative impact on the time and cost of the production process.

Crops with a high starch content have a high value in food applications (both in human and animal feed) and their sugar yield per hectare is low when compared to the potential sugar yield from cellulose and hemi-cellulose crops due to only a small percentage of the total crop being starch. Thus, a process for the derivation of biofuel from alternative sources of biomass, such as lignocellulosic biomass composed primarily of lignin, hemi-cellulose and cellulose, is of great significance to producers because lignocellulosic biomass is an extremely abundant biomass. It includes, e.g., all trees and grasses, as well as agricultural residues such as wet and dry distiller's grains, corn fibre, corn cob and sugarcane bagasse.

The process of deriving biofuel from lignocellulosic biomass will be hereinafter referred to as a “second generation” process. The second generation process converts the lignocellulosic biomass into alcohol (e.g. ethanol) in three stages: a first pre-treatment stage to disrupt the cellular structure of the biomass, a second hydrolysis stage in which the cellulosic part of the biomass is converted to short-chain sugars, and a third fermentation stage in which these sugars are converted to alcohol.

To increase the yield of the hydrolysis, the pre-treatment step is needed to soften the biomass and disrupt its cellular structure, thereby exposing more cellulose and hemi-cellulose material. Disruptive pre-treatment processes are normally chemical or physical in nature. Current chemical pre-treatment processes rely on a catalyst to achieve the desired disruption of the cells of the biomass. This catalyst is commonly an acid or an enzyme. The acid has the disadvantage of being harmful to the environment, whilst enzymes are relatively expensive. The most common physical pre-treatment process is steam explosion, examples of which are disclosed in Neves, U.S. Pat. No. 4,425,433 issued Jan. 10, 1984 and Foody, U.S. Pat. No. 4,461,648 issued Jul. 24, 1984. In steam explosion, the biomass is heated using high pressure steam for a few minutes, before the reactions are stopped by a sudden decompression to atmospheric pressure. A disadvantage of steam explosion is that the process must be contained within a suitable process vessel, and is thus a non-continuous process. Furthermore, the sugar yields from steam explosion are comparatively low while current costs for the process are high.

In both the first and second generation processes, yeast is used to ferment the sugars. However, the yeast is temperature sensitive and the biomass must be cooled to around 30° C. before the yeast can ferment the sugars. Cooling the biomass not only increases the length of the fermentation process, but also increases energy consumption given that the fermented biomass must be re-heated downstream for distillation.

The first generation process described above is the one most commonly used in the biofuel industry at present. In order to reduce the costs of transporting the crops for processing, biofuel processing plants are typically located in close proximity to the areas in which the crops are grown, or in areas with local markets for the two products from the process (e.g. ethanol and animal feed). In an effort to reduce costs still further, the starch-based components of the crop (e.g. corn kernels) are separated from the remainder of the crop (e.g. stalks and leaves) during harvesting, so that only the starch-based components are transported to the processing plant. However, in spite of this separation during harvesting around 10% by weight of the crop transported for processing is made up of lignocellulosic material (e.g. corn husks, corn cob) in which no starch is present. Thus, there is a negligible yield from 10% of the transported crop in a first generation process, even though that 10% is being transported to the processing plant.

A solution to this problem would be to also obtain alcohol from the lignocellulosic material present using the second generation process. However, having both first and second generation processes running alongside one another in a single processing plant has a significant impact on processing costs. Firstly, the set-up costs involved in constructing a processing plant having separate processing lines for the first and second generation processes will be much larger than that for constructing a plant with only a first generation process line. Secondly, the production costs in running the various stages of the two processes alongside one another will also be greater than those associated with running only a first generation process line.

Accordingly, one object of the present invention is to overcome one or more of the aforementioned disadvantages.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a process for the treatment of biomass, comprising:(i) inducing a composition including biomass and a working fluid to flow into a passage of a fluid processing apparatus;(ii) injecting a high velocity transport fluid into the composition through a nozzle communicating with the passage of the fluid processing apparatus, whereby the transport fluid applies a shear force to the composition such that the working fluid is atomised and a vapour and droplet flow regime is formed downstream of the nozzle;(iii) condensing the vapour and droplet flow regime and transferring the composition to a first holding vessel; and(iv) holding the composition in the first holding vessel at a first predetermined temperature for a first predetermined period of time;(v) wherein the process also includes the steps of adding an amylase enzyme and a cellulase enzyme to the composition.

An amylase enzyme is considered to be any enzyme suitable for converting starch to sugar. A cellulase enzyme is considered to be any enzyme suitable for converting cellulose or hemi-cellulose to sugar.

The step of injecting a high velocity transport fluid into the composition through a nozzle may include generating a low pressure region formed downstream of the nozzle.

The condensing step may be initiated by the condensing of the transport fluid downstream of the low pressure region.

The step of transferring the composition to a holding vessel may include passing the composition through a temperature conditioning unit to raise the temperature of the composition to the first predetermined temperature.

The first predetermined temperature may be between 80 and 85 degrees Celsius. The first predetermined temperature may be 83 degrees Celsius.

Alternatively, the first predetermined temperature may be between 72 and 80 degrees Celsius, preferably between 76 and 78 degrees Celsius, such as, for example, 75 degrees Celsius, or 77 degrees Celsius.

The liquefaction enzyme(s), e.g., amylase and/or cellulase enzymes may be added to the composition prior to the composition being induced into the passage of the fluid processing apparatus.

The process may further comprise:(i) transferring the composition to a second holding vessel following the end of the first period of time; and(ii) holding the composition in the second holding vessel at a second predetermined temperature for a second predetermined period of time, wherein the liquefaction enzyme, e.g., an amylase enzyme, may be added to the composition prior to the composition being induced into the passage of the fluid processing apparatus, and another liquefaction enzyme, e.g., a cellulase enzyme, may be added to the composition between the end of the first period of time and the beginning of the second period of time.

Prior to transferring the composition to the second holding vessel, the process may further comprise the step of cooling the composition to the second predetermined temperature.

The first predetermined temperature may be between 80 and 85 degrees Celsius. Preferably, the first predetermined temperature may be 83 degrees Celsius.

The second predetermined temperature may be between 50 and 60 degrees Celsius. Preferably, the second predetermined temperature may be 55 degrees Celsius.

Prior to transferring the composition to the second holding vessel, the process may further comprise:(i) inducing the composition into the passage of a second fluid processing apparatus; and(ii) injecting a high velocity transport fluid into the composition through a nozzle communicating with the passage of the second fluid processing apparatus, whereby the transport fluid applies a shear force to the composition such that the working fluid is atomised for a second time and a second vapour and droplet flow regime is formed downstream of the nozzle, wherein the cellulase enzyme is added to the composition prior to the composition being induced into the passage of the first fluid processing apparatus, and a liquefaction enzyme, e.g., an amylase enzyme, is added to the composition prior to the composition being induced into the passage of the second fluid processing apparatus.

The first predetermined temperature may be between 50 and 60 degrees Celsius. Preferably, the first predetermined temperature may be 55 degrees Celsius.

The second predetermined temperature may be between 80 and 85 degrees Celsius. Preferably, the second predetermined temperature may be 83 degrees Celsius.

The process may further comprise the steps of:(i) cooling the composition to a predetermined fermentation temperature;(ii) adding one or more fermentation agents to the composition; transferring the composition to a fermentation vessel; and(iii) holding the composition in the fermentation vessel at the predetermined fermentation temperature for a predetermined fermentation time.

The cooling step may comprise passing the composition through a cooling vessel. The cooling vessel may be a mash cooler.

The fermentation temperature may be between 30 and 40 degrees Celsius. Preferably, the fermentation temperature may be 35 degrees Celsius.

In the present invention, one or more fermentation agents may be added to the composition. As used herein, “fermentation agents” include well know agents used to facilitate fermentation processes and include, but are not limited to, gluco-amylase and yeast.

The process may further comprise the step of distilling the fermented composition to draw off the alcohol from the remainder of the composition.

The process may further comprise the step of:(i) returning the recovered water or condensate to the composition flowing into the passage of the first fluid processing apparatus.

The process may further comprise the steps of:(i) transferring the remainder of the composition to a separator; and(ii) separating solids from the remainder of the composition.

The process may further comprise the steps of:(i) recovering water content from the separator; and(ii) returning the water content to the composition flowing into the passage of the first fluid processing apparatus.

The process may further comprise the steps of:(i) inducing a portion of the composition to flow into a passage of a second fluid processing apparatus;(ii) injecting a high velocity transport fluid into the composition through a nozzle communicating with the passage of the second fluid processing apparatus, whereby the transport fluid applies a shear force to the composition such that the working fluid is atomised and a second vapour and droplet flow regime is formed downstream of the nozzle;(iii) condensing the second vapour and droplet flow regime and transferring the composition to a second holding vessel; and(iv) holding the composition in the second holding vessel at a second predetermined temperature for a second predetermined period of time;(v) wherein the first fluid processing apparatus and first holding vessel, and the second fluid processing apparatus and second holding vessel operate in parallel; and(vi) wherein the amylase enzyme is added to the composition prior to the induction of the composition into the passage of the first fluid processing apparatus, and the cellulase enzyme is added to the portion of the composition prior to the induction of the portion of the composition into the passage of the second fluid processing apparatus.

The process may further comprise the steps of:(i) cooling each portion of the composition to a predetermined fermentation temperature;(ii) adding one or more fermentation agents to the composition;(iii) transferring the portions of the composition to a fermentation vessel; and(iv) holding the composition in the fermentation vessel at the predetermined fermentation temperature for a predetermined fermentation time.

The fermentation temperature may be between 30 and 40 degrees Celsius. Preferably, the fermentation temperature may be 35 degrees Celsius.

In this embodiment, one or more fermentation agents may be added to the composition. Preferably, two fermentation agents are added, wherein the fermentation agents are gluco-amylase and yeast.

The fermentation of the first and second portions of the composition may be carried out in a single fermentation vessel. Alternatively, the fermentation of the portions of the composition may be carried out in separate fermentation vessels.

The process may further comprise the step of distilling the fermented composition to draw off the alcohol from the remainder of the composition.

The process may further comprise the steps of:(i) transferring the remainder of the composition to a separator; and(ii) separating solids from the remainder of the composition.

The process may further comprise the steps of:(i) recovering the solids content from the separator; and(ii) returning the solids to the second portion of the composition in the passage of the second fluid processing apparatus.

The second portion of the composition may be the solids content recovered from the separator.

The transport fluid may be steam.

The working fluid may be water.

The biomass may comprise one or more starch-based crops.

According to a second aspect of the invention, there is provided a system for treatment of a composition including biomass and a working fluid, the system comprising:(i) at least one fluid processing apparatus, the apparatus having a passage for receiving a supply of the composition, and a transport fluid nozzle having a nozzle outlet opening into the passage and having a throat portion whose cross sectional area is less than that of the outlet;(ii) a first holding vessel in fluid communication with an outlet of the passage; and(iii) a fermentation vessel in fluid communication with the first holding vessel.

The system may further comprise a first cooling vessel located intermediate the first holding vessel and the fermentation vessel.

The system may further comprise a second holding vessel and a second cooling vessel intermediate the first cooling vessel and the fermentation vessel.

The fluid processing apparatus may include one or more additive ports for introducing additives to the composition. An additive port may open into the passage upstream of the nozzle outlet. Alternatively, or in addition, an additive port may open into the passage immediately downstream of the nozzle outlet. The system may further comprise a further additive port adjacent the second holding vessel.

The system may further comprise a second fluid processing apparatus and a second holding vessel downstream of the first holding vessel, the second fluid processing apparatus having a second passage for receiving the composition from the first holding vessel, and a second transport fluid nozzle having a nozzle outlet opening into the second passage and having a throat portion whose cross sectional area is less than that of the outlet.

In another embodiment, the system comprises a first processing line made up of the first fluid processing apparatus and the first holding vessel, and the system further comprises a second processing line comprising:(i) a second fluid processing apparatus, the second fluid processing apparatus having a second passage for receiving a supply of the composition, and a second transport fluid nozzle having a nozzle outlet opening into the second passage and having a throat portion whose cross sectional area is less than that of the outlet; and(ii) a second holding vessel in fluid communication with an outlet of the second passage;(iii) wherein the first and second processing lines are connected in parallel between a supply of the composition and the fermentation vessel.

The system may further comprise a mixing vessel in fluid communication with the inlet to the passage of the fluid processing apparatus, the mixing vessel mixing supplies of biomass and working fluid to form the composition.

The system may further comprise a pump upstream of the or each fluid processing apparatus.

The system may comprise a plurality of fluid processing apparatus connected in series and/or parallel with one another to form an array.

The system may comprise a plurality of second fluid processing apparatus connected in series and/or parallel with one another to form an array.

The system may further comprise a temperature conditioning unit for raising the temperature of the composition between the first and/or second fluid processing apparatus and its respective first and/or second holding vessel.

The system may further comprise a distillation apparatus downstream of the fermentation vessel. The system may further comprise a distillation apparatus downstream of the inlet of the mixing vessel. The system may further comprise a first return line connecting the distillation apparatus to the inlet of the fluid processing apparatus.

The system may further comprise a separation apparatus downstream of the distillation apparatus. The system may further comprise a separation apparatus downstream of the inlet of the mixing vessel. The system may further comprise a second return line which connects the separator to the inlet of the fluid processing apparatus.

The separation apparatus may comprise a centrifuge.

The system may further comprise a transport fluid supply unit in fluid communication with the or each transport fluid nozzle. The transport fluid supply unit may supply transport fluid to both the first and second fluid processing apparatus.

The transport fluid may be steam, and the conditioning unit may be a steam generator.

In another embodiment, the present invention provides bioethanol produced according to the any of the methods or systems disclosed herein. For example, the present invention includes a process for producing bioethanol from a biomass comprising:

(a) inducing at least a first portion of a composition comprising biomass and a working fluid to flow into a passage of a fluid processing apparatus;

(b) injecting a high velocity transport fluid into the composition through a nozzle communicating with the passage of the fluid processing apparatus, whereby the transport fluid applies a shear force to the composition such that the working fluid is atomised and a vapour and droplet flow regime is formed downstream of the nozzle;

(c) condensing the vapour and droplet flow regime;

(d) transferring the composition to a first holding vessel;

(e) holding the composition in the first holding vessel at a first predetermined temperature for a first predetermined period of time, wherein a liquefaction enzyme is added to the composition prior to or during the process;

(f) transferring the composition to a second holding vessel following the end of the first predetermined period of time;

(g) holding the composition in the second holding vessel at a second predetermined temperature for a second predetermined period of time;

(h) cooling the composition to a predetermined fermentation temperature;

(i) adding a fermentation agent to the composition;

(j) transferring the composition to a fermentation vessel; and

(k) holding the composition in the fermentation vessel at the predetermined fermentation temperature for a predetermined fermentation time to generate a fermented composition, which comprises bioethanol.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1is a vertical cross section through a fluid processing apparatus, generally designated10. The processing apparatus10comprises a housing12within which is defined a longitudinally extending passage14. The passage has an inlet16and an outlet18and is of substantially constant circular cross section. In other words, the cross sectional area of the passage12is substantially constant from the inlet16to the outlet18.

A protrusion20extends axially into the housing12from the inlet16and defines exteriorly thereof a plenum22for the introduction of a compressible transport fluid. The plenum22is provided with an inlet24which is connectable to a source of transport fluid (not shown inFIG. 1). The protrusion20defines internally thereof the inlet16and an upstream portion of the passage14. The protrusion20has a distal end26remote from the inlet16. The distal end26of the protrusion20has a thickness which increases and then reduces again so as to define an inwardly tapering surface28. The housing12has a wall30, which at a location adjacent that of the tapering surface28of the protrusion20is increasing in thickness. This increase in thickness provides a portion of the wall30with a surface32which has an inward taper corresponding to that of the tapering surface28of the protrusion20. Between them the tapering surface28of the protrusion20and the tapering surface32of the wall30define an annular nozzle34. The nozzle34has a nozzle inlet36in flow communication with the plenum22, a nozzle outlet40opening into the passage14, and a nozzle throat38intermediate the nozzle inlet36and the nozzle outlet40. The nozzle throat38has a cross sectional area which is less than that of either the nozzle inlet36or the nozzle outlet40. The passage14also includes a mixing region17, which is located in the passage immediately downstream of the nozzle outlet40.

FIG. 2shows a first preferred embodiment of a system for treatment of a biomass composition which incorporates a fluid processing apparatus of the type shown inFIG. 1. A biomass composition is a composition which includes biomass and a working fluid. In the embodiments described herein the preferred working fluid is water, although other fluids suitable for carrying out the process may be used. The term “biomass” is used in this specification to describe any biological material that can be used as a fuel or energy source. Non-limiting examples of suitable types of biomass include forest products, untreated wood products, energy crops and short rotation coppice, as well as animal waste, industrial and biodegradable municipal products from food processing and high energy crops such as rape, sugar cane, and maize. However, whilst not limited to this particular type of biomass, the most preferred biomass for use in the systems and processes of the present invention are starch-based crops such as corn, wheat and barley, for example. The biomass may also be provided for use in the systems and processes of the present invention in a pre-ground form.

The treatment system, generally designated50, comprises a fluid processing apparatus10and a holding vessel52in fluid communication with the outlet18of the processing apparatus10. The holding vessel52is preferably insulated and enclosed by a heated water jacket (not shown) and contains a motor-driven agitator (not shown) to mix and agitate the contents of the vessel52. The system50also comprises a cooling vessel54in fluid communication with the holding vessel52, and a fermentation vessel56in fluid communication with the cooling vessel54. A transport fluid supply58is connected to the plenum inlet24of the processing apparatus10so that transport fluid can be supplied thereto. Although not shown, the system may also comprise a pump upstream of the fluid processing apparatus for inducing fluid into the passage14of the processing apparatus10. Similarly, a temperature conditioning unit (TCU) (not shown) may be included in the system50between the fluid processing apparatus10and the holding vessel52. The TCU comprises one or more fluid processing apparatus of the type illustrated inFIG. 1. Where there is more than one processing apparatus in the TCU, they are preferably arranged in series. The temperature conditioning unit can gently increase the temperature of any fluid passing from the fluid processing apparatus10to the holding vessel52.

The system50enclosed within the dotted lines inFIG. 2can be installed into an existing biomass processing line or, where necessary, additional components can be added to the system50to create a complete biomass processing line. In this case, the system may also comprise a mixing vessel60located upstream of the processing apparatus10and in fluid communication with the inlet16of the apparatus10. The mixing vessel60is preferably enclosed by a heated water jacket (not shown) and has a motor-driven agitator (not shown) for mixing and agitating the contents of the vessel60. The mixing vessel60also includes first and second additive lines62,66which are connected to respective first and second additive supplies64,68. The system may also comprise third and fourth additive lines70,74which are connected to the fermentation vessel56for the supply of fermenting agents thereto from third and fourth additive supplies72,76. A distillation vessel80may be connected in fluid communication with the fermentation vessel56. In addition, there may be provided a holding tank (not referenced) located between the fermentation vessel56and the separation vessel90. The distillation vessel80has an outlet84and may also include a return line82which is in fluid communication with the inlet16of the processing apparatus10, either directly or via the mixing vessel60when present, as shown inFIG. 2. Finally, the system50may also comprise a separation vessel90connected in fluid communication with the distillation vessel80. The separation vessel90preferably comprises a centrifuge and includes a second return line92and a drain line94. As with the return line82of the distillation vessel80, the second return line92is also in fluid communication with the inlet16of the processing apparatus10, either directly or via the mixing vessel60. The drain line94allows contents within the separator90to be removed or drained.

FIG. 3shows a second embodiment of the system, generally designated150. The system150comprises a fluid processing apparatus10of the type shown inFIG. 1, and a first holding vessel52in fluid communication with the outlet18of the processing apparatus10. The system150also comprises a cooling vessel54in fluid communication with the first holding vessel52, and a fermentation vessel56downstream of the cooling vessel54. A transport fluid supply58is connected to the plenum inlet24of the processing apparatus10so that transport fluid can be supplied thereto. Where the second embodiment differs to the first embodiment is that the system150further comprises a second holding vessel152and a second cooling vessel154connected in series with the other components of the system150between the first cooling vessel54and the fermentation vessel56. Both the first and second holding vessels52,152are preferably insulated and enclosed by heated water jackets (not shown) and each contains a motor-driven agitator to mix and agitate the contents of the vessels52,152.

In the system150a first additive supply164is connected to the inlet16of the processing apparatus10by a first additive line162, and the second additive supply168is connected by the second additive line166to the second holding vessel152. The system150may also comprise third and fourth additive lines70,74which are connected to the fermentation vessel56for the supply of fermenting agents thereto from third and fourth additive supplies72,76.

The system150enclosed within the dotted lines inFIG. 3can be installed into an existing biomass processing line or, where necessary, additional components can be added to the system150to create a complete biomass processing line. In this case, the system may also comprise a mixing vessel60located upstream of the processing apparatus10and in fluid communication with the inlet16of the apparatus10. The mixing vessel60is preferably enclosed by a heated water jacket (not shown) and has a motor-driven agitator (not shown) for mixing and agitating the contents of the vessel60. When the mixing vessel60forms part of the system150, the first additive line162may be connected to the mixing vessel60instead of the inlet of the fluid processing apparatus10. A distillation vessel80may be connected to an outlet160of the fermentation vessel56. The distillation vessel80has an outlet84and may also include a return line82which is in fluid communication with the inlet16of the processing apparatus, either directly or via the mixing vessel60when present, as shown inFIG. 3. Finally, the system150may also comprise a separation vessel90connected in fluid communication with the distillation vessel80. The separation vessel90preferably includes a centrifuge and includes a second return line92and a drain line94. As with the return line82of the distillation vessel80, the second return line92is also in fluid communication with the inlet16of the processing apparatus, either directly or via the mixing vessel60. The drain line94allows contents within the separator90to be removed or drained.

FIGS. 4-7show other preferred embodiments of the system of the present invention. As with the first and second embodiments of the system, these additional embodiments of the system may be supplemented with the mixing, distillation and separation vessels shown inFIGS. 2 and 3, but these supplementary vessels are not illustrated or described with respect to these further embodiments for reasons of brevity.

FIG. 4shows a third embodiment of the system of the present invention, generally designated250. The system250comprises a fluid processing apparatus10of the type shown inFIG. 1, and a first holding vessel52in fluid communication with the outlet18of the processing apparatus10. The system250also comprises a cooling vessel54in fluid communication a fermentation vessel56, both of which are downstream of the first holding vessel52. A transport fluid supply58is connected to the plenum inlet24of the processing apparatus10so that transport fluid can be supplied thereto. Where the third embodiment differs to the preceding embodiments is that the system250further comprises a second fluid processing apparatus210and a second holding vessel252connected in series with the other components of the system250between the first holding vessel52and the cooling vessel54. The second processing apparatus210is substantially identical to the first processing apparatus10illustrated inFIG. 1, and has a second transport fluid supply258connected to its respective plenum inlet.

In the system250a first additive supply264is connected to the inlet16of the first processing apparatus10by a first additive line262, whilst the second additive supply268is connected by a second additive line266to the inlet of the second processing apparatus210. The system250may also comprise third and fourth additive lines70,74which are connected to the fermentation vessel56for the supply of fermenting agents thereto from third and fourth additive supplies72,76. The fermentation vessel56has an outlet260.

FIG. 5shows a fourth embodiment of the system of the present invention, generally designated350. The system350comprises first and second processing lines which are in parallel with one another and connected to a shared fermentation vessel56located downstream. The first processing line comprises a first fluid processing apparatus10of the type shown inFIG. 1, a first holding vessel52in fluid communication with the outlet18of the first processing apparatus10, and a first cooling vessel54in fluid communication with the first holding vessel52. A first transport fluid supply58is connected to the plenum inlet24of the first processing apparatus10so that transport fluid can be supplied thereto. The second processing line comprises a second fluid processing apparatus310also of the type shown inFIG. 1, a second holding vessel352in fluid communication with the outlet of the second processing apparatus310, and a second cooling vessel354in fluid communication with the second holding vessel352. The system350may include a second transport fluid supply358for supplying transport fluid to the plenum inlet of the second processing apparatus310.

Both the first and second cooling vessels54,354are in fluid communication with the fermentation vessel56located downstream.

In the system350a first additive supply364is connected to the inlet16of the first processing apparatus10by a first additive line362, whilst the second additive supply368is connected by a second additive line366to the inlet of the second processing apparatus310. The system350may also comprise third and fourth additive lines70,74which are connected to the fermentation vessel56for the supply of fermenting agents thereto from third and fourth additive supplies72,76. The fermentation vessel56has an outlet360which may connect the fermentation vessel56with a distillation vessel and separation vessel of the type shown inFIG. 2in order to supplement the system. Where the distillation vessel and separation vessel are present in the system350, the system350may include respective return lines (not shown) connecting the distillation and separation vessels with the inlet of the second processing apparatus310. The system350may also include a mixing vessel (not shown) upstream of the first and second processing lines, or else dedicated first and second mixing vessels for each of the first and second processing lines.

FIGS. 6 and 7show fifth and sixth embodiments of a system in accordance with the present invention. The systems, generally designated450and550, are similar to the system50shown inFIG. 2. They each have a holding vessel52, a cooling vessel54in fluid communication with the holding vessel52, and a fermentation vessel56in fluid communication with the cooling vessel54. Where the systems450,550differ from the systems of the preceding embodiments is in respect of the fluid processing apparatus. Instead of a single fluid processing apparatus upstream of the holding vessel52, each system450,550utilizes an array of fluid processing apparatus.

In the system450of the fifth embodiment, an array of fluid processing apparatus10is provided in which the apparatus10are arranged in series with one another upstream of the holding vessel52. The array of processing apparatus may share a single transport fluid supply58, as illustrated inFIG. 6, or else each processing apparatus may have its own dedicated transport fluid supply. The system450may include first and second additive lines462,466which connect respective first and second additive supplies464,468to the inlet16of the first fluid processing apparatus10in the array. As with the preceding embodiments, third and fourth additive lines70,74may be present in the system450to connect respective third and fourth additive supplies72,76to the fermentation vessel56.

In the system550of the sixth embodiment, an array of fluid processing apparatus10is provided in which first and second pairs of the apparatus10are arranged in parallel upstream of the holding vessel52. The array of processing apparatus may share a single transport fluid supply, or else each pair of processing apparatus may have a respective first and second transport fluid supply58,558, as shown inFIG. 7. Equally, each individual apparatus10may have its own dedicated supply of transport fluid. The system550may include first and second additive lines562,566which connect respective first and second additive supplies564,568to the inlets16of the first fluid processing apparatus10in each pair forming the array. As with the preceding embodiments, third and fourth additive lines70,74may be present in the system450to connect respective third and fourth additive supplies72,76to the fermentation vessel56.

Preferred embodiments of a process for the treatment of a composition including biomass and a working fluid will now be described, with reference to the accompanying drawings.

A first embodiment of the process utilizes the first embodiment of the system50illustrated inFIG. 2. The composition to be treated includes a mixture of biomass and a working fluid. As stated above, the biomass may be obtained from a wide variety of sources but it is preferred that the biomass is a starch-based crop (e.g. corn). As also stated above, the working fluid is preferably water. The biomass and working fluid may be mixed together to form the composition at a location remote from the system50. Alternatively, if the system50includes the mixing vessel60, the composition can be formed in the mixing vessel60. The ground starch-based crop is introduced into the working fluid in the mixing vessel60at a controlled mass addition flow rate. The introduction of the crop may be done manually or automatically, and may be introduced continuously or as a batch. The mixing of the crop and working fluid leads to the composition forming a slurry. Separately, an amylase enzyme and a cellulase enzyme held in the first and second additive supplies64,68are also added to the composition via the respective first and second additive supply lines62,66. Preferably, the ratio of crop to liquid content in the slurry is 20-40% by weight. Optionally, one or more PH adjusters (e.g. dilute sulphuric acid, ammonia) and/or a surfactant can also be added to the slurry at this point.

The amylase enzyme utilized in each of the embodiments of the treatment process described herein is preferably α-amylase, with an activity of between 750 and 824 AGU/g. The enzyme activity is presented per unit mass of wet crop or feedstock.

Heated water is fed into the water jacket surrounding the mixing vessel60and the heated water jacket then heats the slurry in the vessel60to a temperature of typically 30-60° C., most preferably 30-40° C., and holds the slurry at this temperature for 30-120 minutes. The motor-driven agitator stirs the slurry with gentle (i.e. low shear) agitation whilst the slurry is held in the mixing vessel60.

The slurry is held at the desired temperature in the mixing vessel60for a sufficient period of time to allow the starch content to be prepared for full hydration. When the slurry has been soaked in the mixing vessel60for sufficient time, it is drained from the vessel60and induced into the passage14of the fluid processing apparatus10via the inlet16. The composition may be induced into the fluid processing apparatus10under gravity. Alternatively, if a pump is present, the pump can induce the composition into the fluid processing apparatus10under low shear conditions.

Referring toFIG. 1, when the slurry reaches the fluid processing apparatus10, slurry will pass into the passage14through inlet16and out of the outlet18. A transport fluid, which in this non-limiting example is preferably steam, is fed from the transport fluid supply58at a preferred pressure of between 5-7 Bar to the plenum inlet24. Introduction of the transport fluid through the inlet24and plenum22causes a jet of steam to issue from the nozzle outlet40at a very high, preferably supersonic, velocity. As the steam is injected into the slurry, a momentum and mass transfer occurs between the two which results in the atomization of the working fluid component of the slurry to form a vapour and droplet flow regime. In other words, the working fluid within the composition is broken down into very small droplets which are dispersed in a continuous vapour phase. This transfer is enhanced through turbulence generated in the mixing region17of the passage14by the expansion of the steam as it exits the nozzle34. The steam injected into the mixing region17applies a shearing force to the slurry which not only atomizes the working fluid component but also disrupts the cellular structure of the ground crop suspended in the slurry. This disruption of the cellular structure separates any starch granules present from the crop whilst at the same time exposing as much of the lignocellulosic material also present in the composition as possible.

The temperature and pressure of the composition as it passes through the fluid processing apparatus10can be seen in the graph ofFIG. 8, which shows the profile of the temperature and pressure as the composition passes through various points in the apparatus10ofFIG. 1. The graph has been divided into four sections A-D, which correspond to various sections of the apparatus10. Section A corresponds to the section of the passage14between the inlet16and the nozzle34. Section B corresponds to the upstream section of the mixing region17extending between the nozzle34and an intermediate portion of the mixing region17. Section C corresponds to a downstream section of the mixing region17extending between the aforementioned intermediate portion of the mixing region17and the outlet18, while section D illustrates the temperature and pressure of the composition as it passes through the outlet18.

The steam is injected into the composition at the beginning of section B of theFIG. 8graph. The injection of the steam, preferably at a supersonic velocity, and its expansion upon exiting the nozzle34, generates a low pressure area in the section of the mixing region17immediately downstream of the nozzle34. At a point determined by the steam and geometric conditions, and the rate of heat and mass transfer, the velocity of the steam will reduce and the steam will begin to condense. The steam condensation may continue and form a condensation shock wave in the downstream section of the mixing region17. The forming of a condensation shock wave causes a rapid increase in pressure of the composition, as can be seen in section C ofFIG. 8, and the composition condenses back into a liquid phase in section D ofFIG. 8.

As explained above, as the steam is injected into the composition through nozzle34a pressure reduction may occur in the upstream section of the mixing region17. This reduction in pressure forms an at least partial vacuum in this upstream section of the mixing region17adjacent the nozzle outlet40. Tests have revealed that an approximately 90% vacuum can be achieved in the region17as the steam is injected.

As previously stated, the shear force applied to the composition by the injected steam and the subsequent turbulent flow created disrupts the cellular structure of the ground crop suspended in the slurry. As the slurry passes through the partial vacuum and condensation shock wave formed in the mixing region17, it is further disrupted by the changes in pressure occurring, as illustrated by the pressure profile in sections B and C ofFIG. 8.

As the starch granules are separated from the crop in the apparatus10, the granules are almost instantaneously further hydrated, heated and activated due to the introduction of the steam. The apparatus10simultaneously pumps and heats the composition to complete the hydration and activate or gelatinize the starch content as the slurry passes through. In other words, homogenous swelling of the starch granules will occur due to the granules absorbing water in the presence of heat. This causes the hydrogen bonding between the starch polymers within the granule to loosen, and there is an irreversible breakdown of the crystalline structure inside the granules.

In addition, the apparatus mixes the amylase and cellulase enzymes into the composition, providing a homogenous distribution and high level of contact with the starch and lignocellulosic material in the liquid phase. The temperature of the composition as it leaves the apparatus10is preferably between 74-76° C.

The temperature at which the composition leaves the apparatus10is selected to avoid any heat damage to the composition during the activation of the starch content and disruption of the cells. However, this temperature may be below the temperature for optimal performance of the amylase and cellulase enzymes. The temperature of the composition may therefore need to be raised without subjecting the composition to excessively high temperatures or additional shear forces. This gentle heating may be achieved using the optional temperature conditioning unit (TCU) located between the apparatus10and the holding vessel52.

As described above, the TCU comprises one or more fluid processing apparatus of the type illustrated inFIG. 1. The pressure of the steam supplied to the apparatus making up the TCU is controlled so that it is comparatively low when compared to that of the steam supplied to the fluid processing apparatus10upstream of the TCU. A preferred steam input pressure for the apparatus of the TCU is between 0.5-2.0 Bar. Consequently, the transport fluid velocity is much lower so little or no shear force or condensation shock is applied to the composition by the injected steam as the composition passes through the TCU. Instead, the TCU merely uses the low pressure steam to gently raise the temperature of the composition.

Once it has passed through the TCU, the composition is preferably at a temperature of between 80-85° C., and most preferably 83° C. The composition then flows downstream into the holding vessel52. The water jacket of the holding vessel52receives heated water which maintains the slurry at the aforementioned temperature. If no TCU is present in the system50, the heated water jacket is used to increase the temperature of the slurry to within the desired range and then maintain it. The composition is held in the holding vessel52for a sufficient residence time to allow the amylase and cellulase enzymes to convert the starch, cellulose and hemi-cellulose present into sugars. At the end of the residence time, the composition is transferred to the fermentation vessel56. Thus, the methods and systems of the present invention may be used to generate polysaccharides from a biomass, which may, if desired, be further processed into alcohol, such as ethanol, particularly bioethanol.

The preferred temperature of the composition for fermentation is between 30 and 40° C., and most preferably 35° C. To reduce the temperature of the composition between the holding vessel52and the fermentation vessel56, the composition can be passed through the cooling vessel54, which operates in the same manner as a conventional mash cooler. Alternatively, if the cooling vessel54is not present the composition can be left to cool to the desired temperature in the fermentation vessel56.

Fermentation agents are preferably added to the composition either in the fermentation vessel56or immediately upstream thereof. The agents are contained in the third and fourth additive supplies72,76and delivered into the composition via the respective additive lines70,74. The fermentation agents used may be gluco-amylase and yeast. Once the agents have been added and the composition is within the desired temperature range, the composition is held in the fermentation vessel within the desired temperature range for a sufficient time to allow the agents to convert the sugars present into alcohol, such as, e.g., bioethanol.

Once the fermentation stage has been completed, the composition can be transferred for subsequent distillation and separation. As previously stated, these subsequent processes may or may not be part of the system and process of the present invention. In the distillation vessel80, the composition is boiled and any alcohol (ethanol) present in the composition evaporates and is drawn off via the outlet84. Molecular sieves may be provided downstream of the outlet to remove any remaining impurities in the alcohol. Additionally, there may be provided a water recovery system (not shown) located between the distillation vessel80and the separator vessel90. The remainder of the composition which is left in the distillation vessel80is known as “whole stillage”. This whole stillage is made up of two main constituents: the non-starch elements of the ground crop (also known as “distiller's grains”) and water (also known as “thin stillage”). This whole stillage is transferred from the distillation vessel80into the separation vessel90so that the distiller's grains and thin stillage can be separated from one another. The separation is preferably achieved using a centrifuge. The separated thin stillage can be added back into the composition via the return line92if desired. The distiller's grains can be processed and used as animal feed.

The process employed by the second embodiment of the system150, as shown inFIG. 3, is similar to that employed by the first embodiment of the system50. The composition to be treated includes a mixture of biomass and a working fluid. The biomass is preferably is a starch-based crop (e.g. corn) and the working fluid is preferably water. The biomass and working fluid may be mixed together to form the composition at a location remote from the system150. Alternatively, if the system150includes the mixing vessel60, the composition can be formed in the mixing vessel60. The ground starch-based crop is introduced into the working fluid in the mixing vessel60at a controlled mass addition flow rate. The mixing of the crop and working fluid leads to the composition forming a slurry. Separately, an amylase enzyme held in the first additive supply164is also added to the composition via the first additive supply line162. The first additive line162can supply the amylase enzyme direct to the mixing vessel60, when present, or else to the inlet16of the fluid processing apparatus10. Preferably, the percentage of crop to liquid content in the slurry is 20-40% by weight. Optionally, one or more PH adjusters and/or a surfactant can also be added to the slurry at this point.

Heated water is fed into the water jacket surrounding the mixing vessel60and the heated water jacket then heats the slurry in the vessel60to a temperature of typically 30-60° C., most preferably 30-40° C., and holds the slurry at this temperature for 30-120 minutes. The motor-driven agitator stirs the slurry with gentle (i.e. low shear) agitation whilst the slurry is held in the mixing vessel60.

The slurry is held at the desired temperature in the mixing vessel60for a sufficient period of time to allow the starch content to be prepared for full hydration. When the slurry has been soaked in the mixing vessel60for sufficient time, it is drained from the vessel60and induced into the passage14of the fluid processing apparatus10via the inlet16. The composition may be induced into the fluid processing apparatus10under gravity. Alternatively, if a pump is present, the pump can induce the composition into the fluid processing apparatus10. In such a case a low-shear pump is used. The fluid processing apparatus10is identical to that used in the first embodiment of the process. The manner of operation of the apparatus10, the mechanisms taking place therein, and the resultant effects on the composition are as in the first embodiment of the process, as described above with reference toFIGS. 1 and 8. They will therefore not be described in detail again here.

As the starch granules are separated from the crop in the apparatus10, the granules are almost instantaneously further hydrated, heated and activated due to the introduction of the steam. The apparatus10simultaneously pumps and heats the composition to complete the hydration and activate or gelatinize the starch content as the slurry passes through. In addition, the apparatus mixes the amylase enzyme into the composition, providing a homogenous distribution and high level of contact with the starch material in the liquid phase. The temperature of the composition as it leaves the apparatus10is preferably between 74-76° C.

As with the first embodiment of the process, a temperature conditioning unit (TCU) of the type described above may be included in the system150in order to gently raise the temperature of the composition in the same manner as described above. Once it has passed through the TCU, the composition is preferably at a temperature of between 80-85° C., and most preferably 83° C. The composition is then transferred to the first holding vessel52. The water jacket of the first holding vessel52receives heated water which maintains the slurry at the aforementioned temperature. If no TCU is present in the system150, the heated water jacket is used to increase the temperature of the slurry to within the desired range and then maintain it. The composition is held in the first holding vessel52for a first residence time sufficient to allow the amylase enzyme to convert the starch present in the composition into sugars. At the end of the first residence time, the composition is transferred to the second holding vessel152.

The preferred temperature of the composition when it passes to the second holding vessel152is between 50 and 60° C., and most preferably 55° C. To reduce the temperature of the composition between the first and second holding vessels52,152, the composition can be passed through the cooling vessel54, which operates in the same manner as a conventional mash cooler. Alternatively, if the cooling vessel54is not present the composition can be left to cool to the desired temperature in the second holding vessel152. The heated water jacket of the second holding vessel152maintains the temperature of the composition within the desired range. A cellulase enzyme is added to the composition in the second holding vessel152via the second additive supply168and associated supply line166. The cellulase enzyme is added in order to react with the cellulose and hemicellulose—present in the lignocellulosic material exposed when the composition passed through the fluid processing apparatus10. The composition is held in the second holding vessel152for a second residence time sufficient to allow the cellulase enzyme to convert all of the cellulose and hemi-cellulose present into sugars. At the end of the second residence time, the composition is transferred to the fermentation vessel56.

The preferred temperature of the composition for fermentation is between 30 and 40° C., and most preferably 35° C. To reduce the temperature of the composition between the second holding vessel152and the fermentation vessel56, the composition can be passed through the second cooling vessel154, which operates in the same manner as a conventional mash cooler. Alternatively, if the second cooling vessel154is not present the composition can be left to cool to the desired temperature in the fermentation vessel56.

Fermentation agents are preferably added to the composition either in the fermentation vessel56or immediately upstream thereof. The agents are contained in the third and fourth additive supplies72,76and delivered into the composition via the respective additive lines70,74. The fermentation agents used may be gluco-amylase and yeast. Once the agents have been added and the composition is within the desired temperature range, the composition is held in the fermentation vessel within the desired temperature range for a fermentation time sufficient to allow the agents to convert the sugars present into alcohol.

Once the fermentation stage has been completed, the composition can be transferred for subsequent distillation and separation. In the distillation vessel80, the composition is boiled and any alcohol, such as, e.g., ethanol, present in the composition evaporates and is drawn off via the outlet84. Molecular sieves may be provided downstream of the outlet to remove any remaining impurities in the alcohol. Additionally, there may be provided a water recovery system (not shown) located between the distillation vessel80and the separator vessel90. The remainder of the composition which is left in the distillation vessel80is known as “whole stillage”. This whole stillage is made up of two main constituents: the non-starch elements of the ground crop (also known as “distiller's grains”) and water (also known as “thin stillage”). This whole stillage is transferred from the distillation vessel80into the separation vessel90so that the distiller's grains and thin stillage can be separated from one another. The separation is preferably achieved using a centrifuge. The separated thin stillage can be added back into the composition via the return line92if desired. The distiller's grains can be processed and used as animal feed.

The process employed by the third embodiment of the system250, as shown inFIG. 4, has similarities with those employed by the first and second embodiments of the system50,150. The composition to be treated is formed from a mixture of biomass and a working fluid and prepared in the same manner as described above with respect to the second embodiment. However, it is a cellulase enzyme rather than an amylase enzyme which is initially added to the composition from the first additive supply264. The composition may be induced into the first fluid processing apparatus10under gravity, or a pump can induce the composition into the first fluid processing apparatus10under low shear conditions. Both the first and second fluid processing apparatus10,210employed in this process are identical to that used in the first and second embodiments described above. The manner of operation of the apparatus10,210, the mechanisms taking place therein, and the resultant effects on the composition are as previously described with reference toFIGS. 1 and 8. They will therefore not be described in detail again here.

The first processing apparatus10is used primarily to pre-treat the cellulosic material and mix in the cellulase enzyme. The first processing apparatus10also partially separates the starch granules from the crop and partially hydrates the starch granules. The second processing apparatus210is used to fully hydrate and activate the starch and mix in the starch enzyme. The apparatus mixes the cellulase enzyme into the composition, providing a homogenous distribution and high level of contact with any cellulose and hemi-cellulose that has been exposed by the disruption of lignocellulosic material by the first processing apparatus10. The temperature of the composition as it leaves the first apparatus10is preferably between 50-60° C., and most preferably 55° C. It is then transferred to the first holding vessel52.

The water jacket of the first holding vessel52receives heated water which maintains the slurry at the aforementioned temperature. The composition is held in the first holding vessel52for a first residence time sufficient to allow the cellulase enzyme to convert the cellulose and hemi-cellulose present in the composition into sugars. At the end of the first residence time, the composition is transferred to the second processing apparatus210, at which point an amylase enzyme is added via the second additive supply268.

As stated above, the second fluid processing apparatus210operates in the same manner as the first processing apparatus10, with the same effect on the starch content of the composition. In addition, the apparatus mixes the amylase enzyme into the composition, providing a homogenous distribution and high level of contact with the starch material in the liquid phase. The temperature of the composition as it leaves the second apparatus210is preferably between 74-76° C. As before, a temperature conditioning unit may be present to gently raise the temperature of the composition to between 80 and 85° C. before the composition is transferred to the second holding vessel252. The water jacket of the second holding vessel252receives heated water which maintains the slurry at the aforementioned temperature. If no TCU is present in the system250, the heated water jacket is used to increase the temperature of the slurry to within the desired range and then maintain it. The composition is held in the second holding vessel252for a second residence time sufficient to allow the amylase enzyme to convert the starch present in the composition into sugars. At the end of the second residence time, the composition is transferred to the fermentation vessel56.

As with the previously described embodiments, the preferred temperature of the composition for fermentation is between 30 and 40° C., and most preferably 35° C. To reduce the temperature of the composition between the second holding vessel252and the fermentation vessel56, the composition can be passed through the cooling vessel54, which operates in the same manner as a conventional mash cooler. Alternatively, if the cooling vessel54is not present the composition can be left to cool to the desired temperature in the fermentation vessel56. The fermentation stage is identical to that of the preceding embodiments. Once the fermentation stage has been completed, the composition can be transferred via outlet260for subsequent distillation and separation stages, which may also be the same as those of the preceding embodiments.

The fourth embodiment of the process uses the system350shown inFIG. 5, where the conversion of the starch and cellulose content of the composition into sugars is carried out in first and second process lines running in parallel, before the composition is passed to a shared fermentation vessel56. A biomass and working fluid composition of the type already described above has an amylase enzyme added to it via first additive supply364. The resultant composition is introduced to the first process line and firstly to the first processing apparatus10, whereupon it is atomised by the transport fluid in the same manner as the various fluid processing apparatus already described. Thus, the first fluid processing apparatus10hydrates and activates the starch content of the composition and homogenously mixes the amylase enzyme into the composition.

The temperature of the composition as it leaves the first apparatus10is again preferably between 74-76° C. and is therefore gently heated once out of the first apparatus, either by way of a temperature conditioning unit or by the water-jacketed first holding vessel52, until within the desired 80-85° C. range. The composition is then held in the first holding vessel52for a first residence time sufficient to allow the amylase enzyme to convert the starch content of the composition into sugars. The composition is then transferred to the fermentation vessel56for a fermentation step of the type already described above. A cooling vessel54can reduce the temperature of the composition prior to fermentation, or else the composition may be left to cool in the fermentation vessel56. Following fermentation, the composition is released via outlet360for subsequent distillation and separation.

Solids and distiller's grains obtained from the separation stage are then mixed with additional working fluid and/or liquid components drawn off during distillation or separation to form a further batch of the biomass composition. A cellulase enzyme is added to this composition, which is then induced into the second process line via the second processing apparatus310. The second processing apparatus310operates in the same manner as those already described, with the result that passing the composition through the second processing apparatus310further disrupts the cellular structure of the solid material in the composition and homogenously mixes the cellulase enzyme into the composition. The composition preferably leaves the second apparatus310at a temperature of between 50 and 60° C. and is transferred to the second holding vessel352. The composition is held in the second holding vessel352for a second residence time sufficient for the cellulase enzyme to convert the cellulose and hemi-cellulose exposed in the second apparatus310into sugars. The composition is then transferred for fermentation in the fermentation vessel56, via a second cooling vessel354if necessary.

This embodiment of the process could be modified such that portions of the initial composition are fed to both the first and second process lines simultaneously, with the first line converting the starch content and the second line converting the cellulose and hemi-cellulose content into sugars before both portions of the composition are transferred to the fermentation vessel56. It is therefore not essential that the second process line receives remnants of the composition after the separation stage.

The fifth and sixth embodiments of the process employed by the systems shown inFIGS. 6 and 7are substantially the same as the first and second embodiments of the process as used by the systems ofFIGS. 2 and 3. The formation of the biomass compositions, the addition of amylase and cellulase enzymes, the residence of the processed composition in one or two holding vessels, and the transfer and subsequent fermentation of the composition are the same in these fifth and sixth embodiments as those earlier embodiments. Where the fifth and sixth embodiments differ is that the single fluid processing apparatus has been replaced by an array of fluid processing apparatus. In the fifth embodiment ofFIG. 6, the array is formed from a number of the processing apparatus arranged in series with one another. In the sixth embodiment ofFIG. 7, the array is formed from two pairs of processing apparatus in series, where each pair is in parallel with the other. It should be appreciated that the number of fluid processing apparatuses and configurations of the same could be used in the process and system of the present invention.

The operation of each apparatus, and the mechanisms and effects created therein, are the same as already described. The use of arrays of the type shown inFIGS. 6 and 7maximises the effects of the processing apparatus with respect to the hydration and activation of starch content, the disruption and exposure of lignocellulosic material, and the homogenous mixing of the enzymes with the composition. Use of arrays can also allow the temperature of the composition to be raised more gradually across the array than is possible with a single processing apparatus. This may be achieved by varying the supply pressure and/or density of the transport fluid delivered to each subsequent apparatus in the array to ensure that the desired rise in temperature of the composition is only achieved after the composition has passed through the final apparatus in the array.

Unless otherwise stated the cooling vessels, distillation vessels and separation vessels which may be included in the system of the present invention are conventional arrangements. They have therefore not been described in full detail in this specification.

The present invention provides a single treatment system and process for the conversion of both the starch and cellulose present in a biomass composition. In doing so the present invention maximises the alcohol obtained from the composition, including that from the cellulosic and lignocellulosic material inevitably transported to the processing plant with the collected crop. The cost in transporting this additional material is therefore substantially recouped with the present invention. By converting both the starch and cellulose content together, the present invention provides significant cost savings compared to existing systems in which distinct processes and process lines are needed to convert starch and cellulose content separately.

Further advantages are obtained with the present invention thanks to the use of a fluid processing apparatus of the type described herein. Using a processing apparatus of the type described allows the present invention to heat and activate the starch content of the composition while avoiding the creation of regions of extreme heat, which can damage the starch content. Prevention of these regions also reduces or eliminates Maillard effects caused by the reaction of proteins with the extracted starch. These reactions can prevent conversion of the starch to sugar and therefore reduce yields. Furthermore, the gentle agitation mixing and low shear pumping at a lower temperature also ensures that there are no high shear forces which may damage the starch content of the composition whilst held in one of the holding vessels or being transported between vessels. Such damage limits the ultimate glucose yield available from the feedstock.

The processing apparatus also ensures that the components of the composition are more thoroughly mixed than is possible using simple agitator paddles and/or recirculation loops alone. The atomization of the working fluid further ensures a more homogenous mixing of the composition than previously possible. This improved mixing increases the efficiency of the amylase and cellulase enzymes added to convert the starch and cellulose content to sugars.

As regards conversion of the lignocellulosic material, the shear action and condensation/pressure shock applied to the biomass component of the composition when in the processing apparatus further improves the performance of the present invention as this exposes more of this material present in the biomass. This allows virtually all the starch granules in the feedstock to be separated, thereby providing improved starch activation rates compared to conventional processes as the enzymatic activation is supplemented by the mechanical activation in the processing apparatus. This also allows the process to in particular provide a starch to sugar conversion ratio of substantially 100%. The process of the present invention therefore may only require the composition to pass once through the processing apparatus before it is ready to pass to the holding vessels for the conversion stage. Hence, yields are much improved as there is no time for loss build up during the process.

Exposing more starch also means that less of the amylase enzyme is needed to achieve a desired dextrose equivalent value of 12-18 before the composition is transferred to the fermentation processes. In addition, the condensation/pressure shock kills bacteria at a relatively low temperature, thereby reducing losses in any subsequent fermentation process.

Additionally, injecting a transport fluid such as steam into the biomass composition to atomize the working fluid and create a vapour and droplet flow regime ensures a greater degree of disruption to the cellular structure of the contents of the composition than that achieved by existing pre-treatment processes. Furthermore, as the disruption is at least partially achieved by the transport fluid injection, the invention enables a reduced amount of catalyst or additive to obtain the desired degree of disruption when compared with existing chemical pre-treatment processes. In fact, the disruption achieved by the transport fluid injection may remove the need for such pre-treatment additives entirely. The transport fluid injection of the processing apparatus ensures continual shear and turbulent forces on the composition. The process of the present invention can therefore be continuous, with no need to contain the process in a stand-alone vessel such as that required in steam explosion pre-treatment processes.

The high shear forces imparted by the high velocity transport fluid injection not only assist in the disruption of the cellular structure of the biomass, but also atomize the working fluid component of the composition to ensure intimate and homogenous heating and mixing of the composition with the enzymes. Such improved heating and mixing reduces the amount of time and quantity of enzymes required to achieve the necessary chemical reactions in the holding vessels.

It has also been discovered that the processes and systems of the present invention may also improve fermentation rates in the subsequent fermentation process. The improved hydration of the present invention also hydrates some proteins in the biomass feedstock. These hydrated proteins act as additional feedstock to the fermenting yeast, thereby improving the fermenting performance of the yeast.

Whilst one or more cooling vessels have been described as forming part of the system of the present invention, it is to be understood that these cooling vessels are preferable, rather than essential, components of the system. Whilst cooling vessels allow the temperature of the composition to be lowered between the holding vessels and the fermentation vessels, this cooling could be carried out within the holding vessels or fermentation vessels themselves. Such cooling vessels may include, for example, heat exchangers, chillers, direct injection coolers, cascade coolers, or the like.

The processing apparatus may be modified to include one or more additive ports, thereby allowing the enzymes to be added directly into the processing apparatus instead of the mixing vessel. An additive port may be provided which opens into the passage of the apparatus upstream of the nozzle outlet. Alternatively, or additionally, an additive port may be provided which opens into the passage immediately downstream of the nozzle into the mixing region of the passage.

The arrays of processing apparatus utilized in the fifth and sixth embodiments of the system may replace the individual processing apparatus shown in the other illustrated embodiments. In the embodiments of the present invention where there is more than one fluid processing apparatus present, two or more of these multiple processing apparatus may share a single transport fluid supply. Alternatively, all of the processing apparatus present in the system may share a single transport fluid supply.

Whilst the preferred embodiments of the system described above include additive lines which connect respective additive supplies to the system, these are not essential to the system and process of the present invention. Each additive may be added manually into the system at the desired location without the need for the dedicated supplies and associated supply lines.

It has already been stated that the mixing vessel is a preferred, rather than essential, component of the system of the present invention. Equally, the initial step in the treatment process of forming the composition of biomass and working fluid in the mixing vessel is not essential. If the mixing vessel is not present, the composition may be formed at a remote location and then pumped into the system of the present invention for treatment.

Where the enzymes used require it, the first embodiment of the system and process may be modified such that the temperature of the composition during its residence time in the holding vessel may be between 72 and 80° C., and preferably between 76 and 78° C.

The preferred transport fluid used in the process and system of the present invention is steam. However, alternative transport fluids may be used. An alternative hot, condensable gas such as carbon dioxide, for example, may be used instead.

It should be understood that the process of the present invention is not limited to the use of the specific α-amylase enzyme described above. Alternative amylase enzymes such as β-amylase or λ-amylase may be employed instead. Furthermore, it should also be appreciated that more than one of each type of amylase enzyme and cellulase enzyme may be added to the composition. Other enzymes, i.e., enzymes other than amylase, cellulase, or hemi-cellulase, which are capable of acting on biomass in substantially the same manner as amylase, cellulase, or hemi-cellulase are also contemplated by and within the scope of the present invention.

These and other modifications and improvements may be incorporated without departing from the scope of the invention.