System and method for producing ethanol co-producting feed using wheat

Abstract

The present application relates to the field of ethanol fermentation, and particularly relates to a system and method for producing ethanol and feed from wheat. The system comprises a crushing unit, a fiber water washing unit, a pulp mixing unit, a liquefaction unit, a fermentation unit, a distillation unit, a first separation unit, a second separation unit, an anaerobic unit, an evaporation unit and a drying unit. Due to the cellulose water washing process and twice separation, the clear liquid dry matter is reduced, so that the clear liquid back blending ratio can be as high as 50%. Meanwhile, the amount of clear liquid for evaporation is reduced, and the evaporation load is reduced; the device can be stably operated for a long time, the evaporation unit does not need to be separately stopped for cleaning, and full load operation of the device can be ensured. On the basis of producing ethanol and DDGS products and without increasing energy consumption, the present application adds by-products of fiber feed and protein feed, improves the flexibility of products, and improves the production benefit by more than 10%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ethanol fermentation, in particular to a system and method for producing ethanol and co-producing feed by using wheat. BACKGROUND

[0002] Since wheat and the like are emerging fuel ethanol raw materials, there is no fuel ethanol process specially designed for wheat raw materials in China. Most of the existing process flows are improved from the process flow for producing fuel ethanol from cassava or corn raw materials.

[0003] However, when using wheat raw materials to produce fuel ethanol, the starch content in the components of wheat is low, the non-starch polysaccharide content is high, and the protein content and fiber content are also relatively high. The so-called non-starch polysaccharide (NSP), such as pentosan (about 1.8% soluble pentosan in standard wheat particles), can cause a significant increase in the viscosity of the material, especially a large increase in the viscosity of the supernatant, which generally increases the viscosity of the syrup from about 600 cP when using corn raw materials to about 3000 cP. The increase in the viscosity of the syrup reduces the evaporation capacity; and since the viscosity of the syrup is high, the evaporation device needs to be regularly stopped for cleaning; the proportion of reusable supernatant decreases, the amount of supernatant sent to evaporation increases, and the evaporation energy consumption increases by 10%-20%. Thus, the evaporation unit becomes the bottleneck of the whole wheat ethanol production process, and the load of the whole wheat process device is forced to decrease to about 50% compared to when using corn as raw material to produce ethanol, and the evaporation efficiency becomes the bottleneck of production operation. SUMMARY

[0004] The present application aims to overcome the problems of high viscosity of supernatant and syrup, difficult evaporation, and low reuse of supernatant when using wheat as raw material to produce ethanol in the prior art, and provides a system and method for producing ethanol and co-producing feed by using wheat, which can reduce the concentration of supernatant and the viscosity of syrup, reduce the energy consumption of evaporation, increase the reuse of supernatant, and also co-produce three kinds of feed.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a system for producing ethanol and co-producing feed by using wheat, which comprises:

[0006] a crushing unit for crushing wheat to obtain a crushed product;

[0007] a fiber water washing unit for fiber water washing the crushed product to obtain fiber material and a material to be thickened;

[0008] a thickening unit for thickening the material to be thickened to obtain a starch slurry;

[0009] a liquefaction unit for liquefying the starch slurry to obtain a liquefied liquid;

[0010] a fermentation unit for fermenting the liquefied liquid to obtain a matured mash;

[0011] a distillation unit for distilling the matured mash to obtain ethanol and a waste mash;

[0012] a first separation unit for separating the waste mash to obtain a first clear liquid and a first wet cake;

[0013] a second separation unit for separating the first clear liquid to obtain a second clear liquid and a second wet cake;

[0014] an anaerobic unit for anaerobically treating at least part of the second clear liquid to obtain an anaerobically treated clear liquid and biogas;

[0015] an evaporation unit for evaporating at least part of the second clear liquid to obtain a syrup and an evaporation condensate;

[0016] a drying unit connected by pipelines with the first separation unit, the second separation unit, the fiber washing unit and the evaporation unit, for drying the first wet cake to obtain DDGS, for drying the second wet cake and optionally the syrup to obtain protein feed, and for drying a mixture of the fiber material and at least part of the syrup to obtain fiber feed.

[0017] Preferably, the anaerobic unit is connected by pipelines with the fiber washing unit and / or the slurry preparation unit, for recycling the anaerobically treated clear liquid to the fiber washing unit and / or the slurry preparation unit as washing water and / or slurry preparation water.

[0018] Preferably, the evaporation unit is further connected by pipelines with the fiber washing unit and / or the slurry preparation unit, for recycling the evaporation condensate to the fiber washing unit and / or the slurry preparation unit as washing water and / or slurry preparation water.

[0019] Preferably, the drying unit is further connected by pipelines with the slurry preparation unit and / or the anaerobic unit, for recycling the drying condensate produced by drying to the slurry preparation unit as slurry preparation water, and / or recycling the drying condensate to the anaerobic unit for anaerobic treatment to obtain an anaerobically treated clear liquid and biogas.

[0020] Preferably, the system further comprises a steam generation unit for generating steam from the biogas to obtain biogas source steam; wherein the biogas source steam is used as part of the heat source for the distillation unit and / or the drying unit.

[0021] The second aspect of the present application provides a method for producing ethanol and feed from wheat, which comprises:

[0022] (1) crushing the wheat to obtain a crushed product;

[0023] (2) washing the fiber from the crushed product to obtain fiber material and a material to be pulped;

[0024] (3) pulping the material to be pulped to obtain a starch slurry;

[0025] (4) liquefying the starch slurry to obtain a liquefied liquid;

[0026] (5) fermenting the liquefied liquid to obtain a mature mash;

[0027] (6) distilling the mature mash to obtain ethanol and waste mash;

[0028] (7) first separating the waste mash to obtain a first clear liquid and a first wet cake;

[0029] (8) second separating the first clear liquid to obtain a second clear liquid and a second wet cake;

[0030] (9) anaerobically treating at least part of the second clear liquid to obtain an anaerobically treated clear liquid and biogas;

[0031] (10) evaporating at least part of the second clear liquid to obtain a sugar syrup and an evaporated condensate;

[0032] (11) drying the first wet cake to obtain DDGS, drying the second wet cake and optionally the sugar syrup to obtain protein feed, and drying a mixture of the fiber material and at least part of the sugar syrup to obtain fiber feed.

[0033] Due to the cellulose washing process and the two separations, the dry matter of the clear liquid is reduced, greatly improving the proportion of the clear liquid back blending. The amount of clear liquid to be evaporated is reduced, and the evaporation load is reduced; the device can be operated stably for a long time, and the evaporation unit does not need to be stopped and cleaned separately, which can ensure that the device is operated at full load.

[0034] The present application first separates the cellulose material in the wheat by washing, and then mixes the cellulose material with the sugar syrup obtained by evaporation to produce fiber feed; the waste mash obtained by distillation is subjected to primary separation and secondary separation to produce DDGS feed and protein feed (the protein content is more than 40% by weight).

[0035] The biogas source steam obtained by steam generation treatment of the biogas generated by the anaerobic unit provides heat for the system for producing wheat and feed, although the types of feed produced are increased, but compared with the traditional process, no additional fresh steam is needed, that is, the steam consumption provided by the system is unchanged.

[0036] In summary, the present application increases the by-products of fiber feed and protein feed on the basis of producing ethanol and DDGS products and basically not increasing energy consumption, improves the flexibility of products, and increases the production benefit by more than 10%. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the system for producing ethanol and co-producing feed using wheat, as described in this invention.

[0038] Explanation of reference numerals in the attached figures

[0039] T1, Crushing Unit; T2, Fiber Washing Unit; T3, Slurry Preparation Unit; T4, Liquefaction Unit; T5, Fermentation Unit; T6, Distillation Unit; T7, First Separation Unit; T8, Second Separation Unit; T9, Anaerobic Unit; T10, Evaporation Unit; T11, Drying Unit. Detailed Implementation

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] The first aspect of the present invention provides a system for producing ethanol and co-producing feed using wheat, the system comprising:

[0042] The grinding unit is used to grind wheat to obtain the ground product;

[0043] The fiber washing unit washes the pulverized product to obtain fiber material and material to be slurried.

[0044] The slurry preparation unit is used to prepare the material to be slurry to obtain starch slurry;

[0045] A liquefaction unit is used to liquefy the starch slurry to obtain a liquefied liquid;

[0046] A fermentation unit is used to ferment the liquefied liquid to obtain mature mash.

[0047] A distillation unit is used to distill and separate the mature mash to obtain ethanol and waste mash.

[0048] The first separation unit is used to perform a first separation on the waste mash to obtain a first clear liquid and a first wet cake;

[0049] The second separation unit is used to perform a second separation on the first clear liquid to obtain a second clear liquid and a second wet cake.

[0050] An anaerobic unit is used to anaerobicly treat at least a portion of the second supernatant to obtain anaerobic supernatant and biogas.

[0051] an evaporation unit for evaporating at least part of the second clear liquor to obtain a syrup and an evaporation condensate;

[0052] a drying unit for drying the first wet cake and the second wet cake to obtain DDGS and protein feed, respectively; the drying unit is also connected with the fiber washing unit and the evaporation unit by pipelines for drying the mixture of the fiber material and the syrup to obtain fiber feed.

[0053] The method for producing ethanol from wheat using the system of the present application is as described in the second aspect, which is not repeated here.

[0054] Preferably, the anaerobic unit is connected with the fiber washing unit and / or the slurry preparation unit by pipelines for recycling the clear liquor after anaerobic treatment to the fiber washing unit and / or the slurry preparation unit as washing water and / or slurry preparation water.

[0055] Preferably, the evaporation unit is also connected with the fiber washing unit and / or the slurry preparation unit by pipelines for recycling the evaporation condensate to the fiber washing unit and / or the slurry preparation unit as washing water and / or slurry preparation water.

[0056] Preferably, the drying unit is also connected with the slurry preparation unit and / or the anaerobic unit by pipelines for recycling the dry condensate generated by drying to the slurry preparation unit as slurry preparation water, and / or recycling the dry condensate to the anaerobic unit for anaerobic treatment to obtain the clear liquor after anaerobic treatment and biogas.

[0057] The drying unit can also be connected with the evaporation unit for using the dry exhaust gas as a heat source of the evaporation unit.

[0058] Preferably, the system further comprises a steam generation unit for generating steam from the biogas to obtain biogas source steam; wherein the biogas source steam is used as part of the heat source of the distillation unit and / or the drying unit (preferably for drying fiber feed).

[0059] In the present application, the steam generation unit can also use materials other than biogas as raw materials for generating steam.

[0060] In the present application, the devices or equipment for each unit are conventional equipment in the art, which can be selected by those skilled in the art as needed.

[0061] In the present application, the crushing unit may, for example, comprise a crusher; the fiber water washing unit may comprise a fiber separator and a plurality of water washing tanks, as long as the fiber material in the wheat can be separated from other components, and the specific operating conditions can be adjusted according to the specific fiber water washing equipment; the slurry preparation unit may comprise a slurry preparation tank; the liquefaction unit may comprise a liquefaction tank; the fermentation unit may comprise a fermentation tank, and may further comprise a seed tank for providing seed liquor, and the number of stages and the number of seed tanks can be selected as needed; the distillation unit may comprise at least 2 distillation columns, such as at least a rough distillation column and a rectification column, in order to improve the purity of ethanol, distillation columns (such as combination columns, water washing columns, recovery columns, etc.) can be added; the first separation unit may comprise a plate and frame filter; the second separation unit may comprise a separator; the anaerobic unit may comprise an anaerobic reactor; the evaporation unit may comprise an evaporation device; and the drying unit may comprise a drying machine.

[0062] It should be understood that the above only simply describes the necessary equipment of each unit, and other auxiliary equipment or devices known in the art can also be included in order to maintain the normal operation of the system, which will not be described here. The number of devices in each unit is not particularly limited, and those skilled in the art can adjust as needed.

[0063] The second aspect of the present application provides a method for producing ethanol and co-producing feed using wheat, which comprises:

[0064] (1) crushing the wheat to obtain a crushed product;

[0065] (2) performing fiber water washing on the crushed product to obtain a fiber material and a slurry preparation material;

[0066] (3) performing slurry preparation on the slurry preparation material to obtain a starch slurry;

[0067] (4) performing liquefaction on the starch slurry to obtain a liquefaction liquor;

[0068] (5) performing fermentation on the liquefaction liquor to obtain a mature mash;

[0069] (6) performing distillation on the mature mash to obtain ethanol and a waste mash;

[0070] (7) performing first separation on the waste mash to obtain a first clear liquid and a first wet cake;

[0071] (8) performing second separation on the first clear liquid to obtain a second clear liquid and a second wet cake;

[0072] (9) performing anaerobic treatment on at least part of the second clear liquid to obtain an anaerobically treated clear liquid and biogas;

[0073] (10) subjecting at least part of the second clear liquid to evaporation treatment to obtain a sugar syrup and an evaporation condensate;

[0074] (11) drying the first wet cake, the second wet cake and the mixture of the fiber material and the sugar syrup respectively to obtain DDGS, protein feed and fiber feed.

[0075] In the present application, the use of wheat for producing ethanol means that wheat is used as the main raw material, and the production can be carried out entirely with wheat as the raw material, or other starch raw materials such as rice, corn, cassava and sorghum can be mixed.

[0076] In the present application, the amount of other starch raw materials in the raw material for producing ethanol is not more than 50% by weight, that is, the amount of wheat is not less than 50% by weight.

[0077] It can be understood that the terms "wheat", "corn", "rice", "cassava" and "sorghum" do not refer to the whole plant itself, but to the part or organ with high starch content, that is, wheat seeds, corn seeds, rice seeds, cassava tubers and sorghum seeds, with or without skin.

[0078] In the present application, unless otherwise specified, wheat is grain, rice is brown rice, and corn is corn kernel.

[0079] There is no particular limitation on the pulverization method, which can be various pulverization methods commonly used in the art. In order to improve the effect of subsequent processing, the pulverization conditions are preferably such that more than 80% by weight of the pulverized product can pass through a 20-mesh screen, further preferably at least 85%, and still further preferably at least 95% of the pulverized product can pass through a 20-mesh screen.

[0080] Generally, the fiber washing equipment can be composed of a series of water washing tanks and corresponding equipment (such as fiber separators and pumps, etc.) connected in series. The direction of the feed into the tank and the water is countercurrent, and the discharge of the first tank can enter a separation device (such as a plate and frame filter or a centrifuge), to obtain fiber material and liquid phase, and the liquid phase enters the next tank, and after repeated water washing, the material in the last tank enters a slurry preparation unit. The equipment operates at normal temperature and pressure.

[0081] It should be understood that the material to be slurried can also contain cellulose, and the fiber material can also contain starch. Preferably, the fiber washing conditions are such that the cellulose content in the material to be slurried is 0.8% by weight or less, and the starch content in the fiber material is 3% by weight or less.

[0082] Preferably, the content of solid in the starch slurry is 20-40% by weight, for example 20, 25, 30, 35, 40% by weight and any value within the range consisting of any two of them, more preferably 25-32% by weight.

[0083] Preferably, the temperature of the slurry is 90-105°C, preferably 93-100°C, which can make the starch completely gelatinized and the starch in the material fully released, providing good conditions for subsequent liquefaction and facilitating the increase of ethanol concentration.

[0084] Preferably, the slurry process further comprises a step of adjusting the pH, and the adjusted pH is preferably 3-8, more preferably 4-7.

[0085] Preferably, the water used in the slurry step is at least partially from at least one of the following: the clear liquid after anaerobic treatment, the evaporation condensate and the drying condensate.

[0086] In the present application, preferably, the slurry method further comprises: slurring the material to be slurried in the presence of a high-temperature enzyme preparation to obtain a starch slurry; wherein the high-temperature enzyme preparation comprises xylanase and / or β-glucanase.

[0087] In the present application, the high-temperature enzyme preparation refers to an enzyme preparation that can withstand a temperature of 90°C or above. Both the xylanase and the β-glucanase involved should have the property of being able to withstand a temperature of 90°C or above.

[0088] When used alone, preferably, the amount of xylanase used is 10-40U per 1g of wheat, further preferably 12-20U, for example 12U, 13U, 14U, 15U, 16U, 17U, 18U, 19U, 20U and any value within the range consisting of any two of them. It can be obtained by commercial purchase, for example, it can be Viscozyme HT purchased from Novozymes.

[0089] When used alone, preferably, the amount of β-glucanase used is 5-20U per 1g of wheat, further preferably 10-18U, for example 10U, 11U, 12U, 13U, 14U, 15U, 16U, 17U, 18U and any value within the range consisting of any two of them. It can be obtained by commercial purchase, for example, it can be high-temperature β-glucanase purchased from Boli Company or Bostar.

[0090] When xylanase and β-glucanase are used together, preferably, the amount of xylanase used is 10-15U per 1g of wheat, and the amount of β-glucanase used is 1-2U.

[0091] The inventors have also tried adding cellulase for slurry, but there is basically no effect.

[0092] In the present application, the order of adding various enzymes in the high-temperature enzyme agent above has no limitation.

[0093] In the present application, the purpose of the liquefaction is to convert the starch slurry into fermentable sugar. Therefore, any method that can achieve the purpose of liquefaction treatment conventionally used in the art is suitable for the present application. Specifically, the process of the liquefaction can include adding amylase to the starch slurry for liquefaction to obtain a liquefied liquid.

[0094] Specifically, the process of the liquefaction can be performed separately after the slurry preparation step (such as adding amylase to the starch slurry for liquefaction to obtain a liquefied liquid) or simultaneously with the slurry preparation (such as adding amylase to the starch slurry for slurry preparation together with xylanase and / or β-glucanase).

[0095] Preferably, the amount of the amylase is 10-80 U, more preferably 18-40 U, per 1 g of the ground product.

[0096] It should be understood that the ground product herein can refer to wheat (when whole wheat is used for ethanol production) or a mixture of wheat and other starchy raw materials (when wheat and other starchy raw materials are used for ethanol production).

[0097] The amylase can be any amylase conventionally used in the art, such as a high-temperature resistant α-amylase available from Genencor.

[0098] Preferably, the conditions of the liquefaction include a temperature of 55-120°C, more preferably 70-100°C; a pH of 3-8, more preferably 4-7; and a time of 0.2-10 h, more preferably 2-5 h.

[0099] In the present application, the purpose of the fermentation is to produce an ethanol-containing fermentation broth by fermenting the liquefied liquid, and to obtain a mature broth after separation. Therefore, any method that can achieve the purpose of fermentation conventionally used in the art is suitable for the present application.

[0100] Specifically, the process of the fermentation can include inoculating a strain into the liquefied liquid for fermentation; the pH of the fermentation is 2-7, preferably 3-6; the temperature is 25-40°C, preferably 30-35°C; and the time is 2-5 days. Under the preferred conditions, the yield of ethanol can be improved.

[0101] The strain for fermentation can be any strain that can utilize C5 sugar and C6 sugar to produce ethanol simultaneously, preferably, the utilization rate of the strain for producing ethanol from pentose sugar is 60% or more, based on the total weight of arabinose and xylose. For example, it can be Saccharomyces cerevisiae CGMCC No. 16830.

[0102] It should be understood that the utilization rate of pentose sugar in large-scale production of ethanol is lower than the data in small or pilot scale, that is, the utilization rate of pentose sugar can be higher if it is in small or pilot scale or laboratory scale.

[0103] In the present application, the strain can also be activated and at least one stage of expansion before inoculation, the activation can be carried out in a shake flask, the expansion can be carried out in a shake flask and / or an expansion tank. For example, the activation and the first stage of expansion can be carried out in a shake flask, and the second stage of expansion can be carried out in an expansion tank to obtain a seed liquid.

[0104] The conditions of activation and each stage of expansion can include: pH value of 2-7, preferably 3-6; temperature of 25-40℃, preferably 30-35℃; activation time of 12-24h; each stage of expansion time of 6-16h.

[0105] In the present application, the inoculation amount of the strain can be selected within a wide range, for example, the inoculation amount of the strain can be 1×10 4 -1×10 7 cfu, relative to 1 gram of the liquefaction liquid.

[0106] The culture medium used in the activation or expansion process can be the same or different, and can be the conventional expansion culture medium used in the art, such as YEPX culture medium or enzymatic hydrolysis liquid culture medium.

[0107] The YEPX culture medium can include 5-15g / L yeast extract, 15-25g / L peptone and 15-25g / L monosaccharide. The monosaccharide is selected from at least one of glucose, arabinose and xylose.

[0108] The enzymatic hydrolysis liquid culture medium can include enzymatic hydrolysis liquid diluent, monosaccharide and corn syrup.

[0109] Preferably, the content of glucose is 2.5-3.5 parts by weight, the content of xylose is 1-1.5 parts by weight, the content of corn syrup is 0.1-0.2 parts by weight, and the balance is enzymatic hydrolysis liquid diluent (dilution ratio is preferably 1-2 times), relative to 100 parts by weight of the enzymatic hydrolysis liquid culture medium, under the preferred conditions, the tolerance of the strain to the inhibitors contained in the enzymatic hydrolysis liquid is improved.

[0110] Preferably, the expansion culture medium further comprises penicillin, and the amount of penicillin is such that the content of penicillin in the expansion culture medium is 5-20ppm, more preferably 8-15ppm.

[0111] In the present application, the fermentation is such that the utilization rate of pentose is 60% or more, preferably 65% or more, and more preferably 70% or more, based on the total weight of arabinose and xylose.

[0112] In the present application, the utilization rate of pentose can be calculated according to the following formula: utilization rate of pentose (%) = (pentose concentration at 0 h of fermentation - pentose concentration at the end of fermentation) / pentose concentration at 0 h of fermentation x 100%, wherein the pentose is based on the total weight of arabinose and xylose.

[0113] In the present application, saccharification and fermentation can be carried out simultaneously, i.e. saccharifying enzyme is also added to the liquefied liquid, wherein the saccharifying enzyme can be a saccharifying enzyme commonly used in the art, such as Novozyme's Shuhong 474.

[0114] The amount of the saccharifying enzyme can be selected within a wide range, preferably, the amount of the saccharifying enzyme is 300-400 U, preferably 320-380 U, per 1 g of the crushed product.

[0115] Preferably, the method further comprises adding cellulase in at least one of the steps of slurrying, liquefying and fermenting. In the preferred case, the solid content of the clear liquid can be further reduced, the viscosity of the syrup can be reduced, and the yield of ethanol can be increased.

[0116] Preferably, the amount of the cellulase is 5-20 U, preferably 10-18 U, per 1 g of the wheat, for example, 10 U, 11 U, 12 U, 13 U, 14 U, 15 U, 16 U, 17 U, 18 U, and any value within the range formed by any two of them. It can be obtained commercially, for example, cellulase available from Boli Company or Baisjie.

[0117] In the present application, the purpose of the distillation is to extract ethanol from the fermented mash, and the mode of the distillation preferably comprises: subjecting the matured mash to rough distillation to obtain a rough distillation fraction and a waste mash; subjecting the rough distillation fraction to rectification to obtain ethanol.

[0118] The distillation can be carried out in a distillation system commonly used in the art, which can be selected by those skilled in the art as needed.

[0119] The rough distillation can be carried out in a rough distillation column, and the working conditions of the rough distillation column preferably comprise: a column bottom temperature of 65-85°C; a column bottom pressure of -0.06 to -0.03 MPa; a column top temperature of 40-60°C; a column top pressure of -0.05 to -0.08 MPa; and a reflux ratio of 0.5-5.

[0120] The distillation can be carried out in a distillation column, preferably under working conditions including a column bottom temperature of 105-125°C, a column bottom pressure of 0.07 to 0.3 MPa, a column top temperature of 85-98°C, a column top pressure of 0.05 to 0.2 MPa, and a reflux ratio of 0.5-8.

[0121] In the present application, the reflux ratio refers to the ratio of the amount of the withdrawn material to the amount of the material returned to the column.

[0122] The waste beer from the crude distillation column is discharged from the column bottom, and the ethanol content in the waste beer is preferably <0.04% by weight, which can be subjected to post-treatment, such as separation, evaporation and drying to obtain a by-product.

[0123] It should be understood that the distillation unit can further comprise other distillation columns, each of which is operated under conventional working conditions in the art, which will not be described herein.

[0124] In the present application, the method further comprises: subjecting the waste beer to a first separation to obtain a first clear liquid and a first wet cake, and subjecting the first clear liquid to a second separation to obtain a second clear liquid and a second wet cake.

[0125] In the present application, the separation method can use conventional technical means in the art, such as separation by centrifugation or filtration. It should be understood that the first separation is a coarse separation, and the second separation is a fine separation.

[0126] Preferably, the first separation is carried out under conditions such that the dry matter content in the first clear liquid is 5-10% by weight.

[0127] Preferably, the second separation is carried out under conditions such that the dry matter content in the second clear liquid is ≤3.5% by weight.

[0128] In a preferred embodiment of the present application, the first separation is carried out by plate-and-frame filtration or centrifugation (at a speed of 1500-2000 rpm).

[0129] In a preferred embodiment of the present application, the second separation is carried out by centrifugation (at a speed of 2000-2500 rpm).

[0130] It should be understood that when both the first and second separations are carried out by centrifugation, the speed of the second separation is higher than that of the first separation.

[0131] In the present application, the main component in the second clear liquid obtained after the second separation is sugar, and the second clear liquid is divided into two streams, one of which is subjected to anaerobic treatment, and the other of which is subjected to evaporation treatment.

[0132] Preferably, the second liquor subjected to anaerobic treatment accounts for 30-70% by volume, more preferably 40-60% by volume, of the total volume of the second liquor. In the preferred case, the entire liquor can be recycled.

[0133] The evaporation can produce sugar syrup and evaporation condensate, or the evaporation can produce anaerobically treated liquor and biogas.

[0134] The anaerobic treatment can be performed in an anaerobic reactor, such as a methane generator. The second liquor treated by the anaerobic reactor can produce biogas and anaerobically treated liquor, the biogas can provide heat energy for the production of ethanol by combustion, and the anaerobically treated liquor can be recycled.

[0135] In the anaerobic process, the specific operating conditions can be selected according to the actual situation, such as the growth and reproduction of anaerobic bacteria, preferably the temperature of anaerobic fermentation is controlled at 25-35℃, and the pH is controlled at 6.5-7.5. The anaerobic reactor can work continuously or intermittently, preferably continuously.

[0136] Preferably, the COD value of the anaerobically treated liquor is below 200mg / L, which can then be used as at least part of the water for sizing in the sizing step or part of the water for washing in the fiber washing step.

[0137] Preferably, the method further comprises recycling the anaerobically treated liquor and / or the evaporation condensate to the fiber washing step and / or the sizing step as water for washing and / or water for sizing.

[0138] Preferably, the method further comprises steam generation from the biogas to obtain biogas source steam; wherein the biogas source steam is used as part of the heat source for the distillation step and / or the drying step. For example, the biogas source steam can be used for drying to produce fiber feed.

[0139] In the present application, the method further comprises: evaporating at least the second liquor to obtain sugar syrup and evaporation condensate.

[0140] The person skilled in the art can select the device and parameters of evaporation according to the needs.

[0141] In the present application, the method further comprises: drying the first wet cake to obtain DDGS; drying the second wet cake and optionally the sugar syrup to obtain protein feed; and drying the mixture of the fiber material and at least part of the sugar syrup to obtain fiber feed.

[0142] The DDGS refers to distiller's dried grains with solubles, which can be used as a feed product.

[0143] The protein content of the protein material is in the range of 40-60% by weight, and can also be used as feed. In the production of the protein material, the second wet cake can be dried entirely to obtain the protein feed, or the second wet cake and the syrup can be mixed and dried to obtain the protein feed.

[0144] In the present application, the syrup used in the production of the protein material is in the range of 0-50% by volume of the total volume of the syrup. In this case, the color of the protein feed is better and uniform. In the present application, most or even all of the syrup can be mixed with the fiber material and dried to produce the fiber feed.

[0145] In the present application, the drying method can be a conventional technique used in the art, such as drying by a drying machine. The temperature and time of drying can be adjusted as needed by those skilled in the art.

[0146] The fiber feed and the DDGS feed can be dried at atmospheric pressure; the high-protein feed is dried under vacuum, with a vacuum degree controlled at -0.04 to -0.07 MPaG, to ensure that the color of the protein feed is good.

[0147] After the first wet cake is dried to obtain DDGS, the dry exhaust gas obtained still contains a high amount of heat, which is generally used in the drying unit, such as the drying of the protein feed and / or the fiber feed.

[0148] In the present application, preferably, the dry exhaust gas is used as a heat source for the evaporation step and / or a heat source for the drying of the protein feed, and the biogas source steam is used as a heat source for the drying of the fiber feed. In this case, the heat can be fully utilized.

[0149] Preferably, the method further comprises recycling the dry condensate produced in the drying step to the slurry preparation step as slurry preparation water, and / or recycling the dry condensate to the anaerobic step for anaerobic treatment to obtain anaerobically treated clear liquid and biogas.

[0150] In the present application, the ethanol obtained by distillation can be subjected to post-treatment to obtain an ethanol product. Those skilled in the art can select a suitable purification process as needed, which is not described here.

[0151] In the present application, the pressure is all gauge pressure unless otherwise specified.

[0152] According to a particularly preferred embodiment of the present application, the present application provides a method for producing fuel ethanol using wheat raw materials, which comprises:

[0153] (1) crushing the wheat to obtain a crushed product; wherein the crushing conditions enable more than 80% by weight of the crushed product to pass through a 20-mesh screen;

[0154] (2) washing the crushed product with water to obtain fiber material and a material to be pulped, the conditions of the water washing being such that the starch content in the fiber material is 3% by weight or less and the cellulose content in the material to be pulped is 0.8% by weight or less; wherein the water used for the washing includes at least one of process water and condensate from evaporation and clear liquid after anaerobic treatment;

[0155] (3) mixing the material to be pulped with alpha-amylase, xylanase, beta-glucanase and water for pulping to obtain starch slurry, wherein the conditions of the pulping include a temperature of 93-97°C and a pH of 4-6; the amount of water for pulping being such that the solid content in the obtained starch slurry is 25-32% by weight, wherein the water for pulping includes at least one of process water and condensate from evaporation, clear liquid after anaerobic treatment and dry condensate; wherein the amount of xylanase is 10-15 U and the amount of beta-glucanase is 1-2 U per 1 g of wheat; wherein the amount of alpha-amylase is 18-25 U per 1 g of the crushed product;

[0156] (4) liquefying the starch slurry to obtain a liquefied liquid; the conditions of the liquefying being a temperature of 85-95°C, a time of 1-2 h and a pH of 4-6;

[0157] (5) inoculating the liquefied liquid with a strain in the presence of saccharifying enzyme to perform fermentation and obtain a mature mash; the inoculation amount of the strain being 1 x 10 4 -1 x 10 6 cfu per 1 g of the liquefied liquid; the conditions of the fermentation being a temperature of 30-34°C, a pH of 3.5-4.5 and a time of 60-72 h; wherein the amount of saccharifying enzyme is 320-380 U per 1 g of the crushed product;

[0158] (6) performing crude distillation on the mature mash to obtain waste mash and a crude distillation fraction, and performing refined distillation on the crude distillation fraction to obtain ethanol;

[0159] (7) performing first separation on the waste mash to obtain a first wet cake and a first clear liquid, and performing second separation on the first clear liquid to obtain a second wet cake and a second clear liquid; wherein the conditions of the first separation are such that the dry matter content in the first clear liquid is 5-10% by weight, and the conditions of the second separation are such that the dry matter content in the second clear liquid is 3.5% by weight or less;

[0160] evaporating 45-55% by volume of the second clear liquor to obtain a syrup and an evaporated condensate; anaerobically treating the remaining second clear liquor to obtain biogas and an anaerobically treated clear liquor, and steam generating the biogas to obtain a biogas source steam; wherein the anaerobic treatment is under conditions such that the COD value of the anaerobically treated clear liquor is less than 200 mg / L; wherein the biogas source steam is used as at least part of the heat source for the distillation step and / or the heat source for drying the fibrous feed;

[0161] first drying the first wet cake to obtain DDGS and a dry waste gas; mixing at least part of the syrup with the fibrous feed and second drying to obtain the fibrous feed; mixing the remaining syrup with the second wet cake and third drying to obtain the protein material; wherein the dry waste gas is used as the heat source for the evaporation step and the drying of the protein feed; and recycling the dry condensate from the drying step to the slurrying step as the slurrying water and / or anaerobically treating the dry condensate to obtain the anaerobically treated clear liquor and the biogas.

[0162] wherein the wheat can be used together with other starchy materials (the other starchy materials being less than 50% by weight of the starchy materials used to produce the ethanol) to produce the ethanol, and the whole wheat can be used to produce the ethanol.

[0163] In the following examples and comparative examples, unless otherwise specified, the reagents used are commercially available.

[0164] Unless otherwise specified, the equipment used is conventional in the art, and the person skilled in the art can select and operate it according to the actual situation.

[0165] The Saccharomyces cerevisiae is Saccharomyces cerevisiae CGMCC No. 16830.

[0166] The xylanase is Viscozyme HT purchased from Novozymes;

[0167] The β-glucanase is β-glucanase purchased from BSG;

[0168] The α-amylase is purchased from Genencor;

[0169] The glucoamylase is Shuhong 474 purchased from Novozymes.

[0170] The YEPX medium: 10 g / L of yeast extract, 20 g / L of peptone, 20 g / L of xylose, and 10 ppm of penicillin.

[0171] A steam generator is used to generate fresh steam at 0.80 MPaG to provide the heat source for the distillation column.

[0172] The method for measuring the solid content in the clear liquid is the drying method, and the solid content = the weight of the solid phase after drying / the weight of the clear liquid before drying.

[0173] The viscosity is measured by a viscosity tester.

[0174] The water consumption and steam consumption are respectively the weight of fresh process water and steam (not including biogas source steam) consumed per 1 t of ethanol produced.

[0175] The energy consumption is the energy consumed per 1 t of ethanol produced.

[0176] In the following examples, the ethanol production scale is 300,000 tons / year of fuel ethanol.

[0177] Unless otherwise specified, the following point values are within the range expected in the art.

[0178] Example 1

[0179] This example is used to illustrate the system and method for producing ethanol and co-producing feed using wheat according to the present application.

[0180] In the system as shown in Figure 1 , the preparation of ethanol and co-produced feed is carried out, and the system comprises:

[0181] A crushing unit T1 is used to crush the wheat to obtain a crushing product;

[0182] A fiber washing unit T2 is used to wash the fibers of the crushing product to obtain fiber material and material to be thickened;

[0183] A thickening unit T3 is used to thicken the material to be thickened to obtain starch slurry;

[0184] A liquefaction unit T4 is used to liquefy the starch slurry to obtain liquefied liquid;

[0185] A fermentation unit T5 is used to ferment the liquefied liquid to obtain mature mash;

[0186] A distillation unit T6 is used to distill and separate the mature mash to obtain ethanol and waste mash;

[0187] A first separation unit T7 is used to first separate the waste mash to obtain first clear liquid and first wet cake;

[0188] A second separation unit T8 is used to second separate the first clear liquid to obtain second clear liquid and second wet cake;

[0189] an anaerobic unit T9, configured to perform anaerobic treatment on at least part of the second clear liquor to obtain anaerobically treated clear liquor and biogas; connected to the fiber washing unit T2 and / or the slurrying unit T3 by pipelines, configured to recycle the anaerobically treated clear liquor to the fiber washing unit T2 and / or the slurrying unit T3 as washing water and / or slurrying water;

[0190] an evaporation unit T10, configured to perform evaporation treatment on at least part of the second clear liquor to obtain sugar syrup and evaporation condensate; connected to the fiber washing unit T2 and / or the slurrying unit T3 by pipelines, configured to recycle the evaporation condensate to the fiber washing unit T2 and / or the slurrying unit T3 as washing water and / or slurrying water;

[0191] a drying unit T11, connected to the first separation unit T7, the second separation unit T8, the fiber washing unit T2 and the evaporation unit T10 by pipelines, configured to dry the first wet cake to obtain DDGS, dry the second wet cake and part of the sugar syrup to obtain protein feed, and dry the mixture of the fiber material and at least part of the sugar syrup to obtain fiber feed; the drying unit T11 is also connected to the slurrying unit T3 and / or the anaerobic unit T9 by pipelines, configured to recycle the drying condensate generated by drying to the slurrying unit T3 as slurrying water, and / or recycle the drying condensate to the anaerobic unit T9 for anaerobic treatment to obtain anaerobically treated clear liquor and biogas;

[0192] a steam generation unit, configured to perform steam generation on the biogas to obtain biogas source steam; wherein the biogas source steam is used as at least part of the heat source of the distillation unit T6 and the drying unit T11.

[0193] The specific method is as follows:

[0194] Wheat is subjected to crushing treatment to obtain a crushing product. The crushing conditions are such that more than 80% by weight of the crushing product can pass through a 20-mesh screen. After fiber washing of the crushing product in a fiber washing device, a fiber material and a material to be slurried are obtained, and the fiber washing conditions are such that the starch content in the fiber material is less than 2.8% by weight, and the cellulose content in the material to be slurried is less than 0.68% by weight. The washing water includes process water, evaporation condensate and anaerobically treated clear liquor.

[0195] The slurry material to be adjusted is sent to a slurry tank to be mixed with α-amylase, xylanase and β-glucanase and slurry water to perform slurry adjustment, to obtain a starch slurry, the slurry adjustment temperature is 95℃, the amount of slurry water is such that the solid content of the obtained starch slurry is 28% by weight, and the pH of the starch slurry is 5. After slurry adjustment, direct liquefaction is performed without adding α-amylase, the liquefaction conditions are: temperature is 90℃, time is 90 minutes, and pH is 5.6. Among them, the slurry water includes process water, evaporation condensate, clear liquid after anaerobic treatment and dry condensate. Among them, the amount of xylanase is 12U compared to 1g of wheat, and the amount of β-glucanase is 1.5U; the amount of α-amylase is 20U relative to 1g of the crushed product.

[0196] The Saccharomyces cerevisiae is activated and expanded with YEPX medium to obtain a seed liquid. Among them, the activation conditions include: temperature is 30℃, initial pH is 5, and time is 20h; the expansion conditions include: temperature is 30℃, initial pH is 5, and time is 12h. The saccharifying enzyme, liquefied liquid and seed liquid are mixed to perform fermentation, wherein the inoculation amount of the alcohol yeast is 10 5 cfu relative to 1g of the above liquefied liquid, and the fermentation conditions are: fermentation temperature is 32℃, pH is 4.2, and fermentation time is 65h, to obtain a fermentation mash, and a mature mash is obtained after filtration. Among them, the amount of saccharifying enzyme is 350U relative to 1g of the crushed product.

[0197] The mature mash is subjected to rough distillation in a rough distillation column to obtain a waste mash and a rough distillation fraction, and the obtained rough distillation fraction is subjected to rectification in a rectification column to obtain ethanol. Among them, the rough distillation conditions include: column bottom temperature is 80℃; column bottom pressure is-0.045MPa; column top temperature is 53℃; column top pressure is-0.065MPa; and reflux ratio is 0.8. The rectification conditions include: column bottom temperature is 105℃; column bottom pressure is 0.13MPa; column top temperature is 92℃; column top pressure is 0.07MPa; and reflux ratio is 3.

[0198] The waste mash is subjected to first separation in a plate and frame filter to obtain a first wet cake and a first clear liquid; the first clear liquid is subjected to second separation in a disc separator (rotating speed is 2000rpm) to obtain a second wet cake and a second clear liquid. Among them, the solid content in the first clear liquid is 8.15% by weight; and the dry matter content in the second clear liquid is reduced to 3.2% by weight.

[0199] The 50% by volume of the second clear liquor is evaporated to obtain a syrup and an evaporated condensate; the remaining second clear liquor is subjected to anaerobic treatment in an anaerobic reactor to obtain biogas and an anaerobically treated clear liquor. The anaerobic treatment is carried out under conditions such that the COD value of the anaerobically treated clear liquor is less than 200 mg / L. The biogas is subjected to steam generation to obtain biogas source steam; wherein the biogas source steam is used as a heat source for drying the fibrous feed.

[0200] The first wet cake is dried by a dryer to obtain DDGS and a dry exhaust gas. 20% by volume of the syrup is mixed with the fibrous raw material and dried to obtain the fibrous feed; the remaining amount of the syrup is mixed with the second wet cake and dried to obtain the protein feed. The dry exhaust gas can provide a heat source for the evaporation step and the production of the protein feed. The dry condensate produced in the drying step is recycled to the slurrying step and / or the anaerobic step to be used as the slurrying water, or subjected to anaerobic treatment to obtain an anaerobically treated clear liquor and biogas.

[0201] For the production of 1 t of ethanol (95% by volume), 0.6 kg of DDGS, 0.35 kg of protein feed and 0.15 kg of fibrous feed are co-produced.

[0202] The solid content of the first clear liquor, the second clear liquor and the syrup and the viscosity of the syrup are determined, and the specific results are shown in Table 1; the water consumption, the steam consumption (excluding biogas source steam) and the energy consumption for the production of 1 t of ethanol (95% by volume) are shown in Table 2.

[0203] The device is stably operated for a long time, the evaporation unit does not need to be shut down for cleaning, and full load operation of the device can be ensured; the clear liquor is completely recycled, and a wastewater treatment plant does not need to be set up.

[0204] Comparative Example 1

[0205] This comparative example illustrates a reference method for producing ethanol co-produced with feed using wheat.

[0206] The system and method described in Example 1 are operated, except that the system does not contain a fibrous water washing unit, and the crushed product is directly subjected to slurrying.

[0207] Since the fibers are not separated, only two products, DDGS and high-protein feed, can be produced, and for the production of 1 t of ethanol (95% by volume), 0.7 kg of DDGS and 0.3 kg of protein feed are co-produced, and there is 0 kg of syrup (the syrup of the fibrous feed is used to produce DDGS feed).

[0208] In addition, since the fibers are not separated, the efficiency of the subsequent separation equipment is poor, the moisture content of the wet cake increases, and the energy consumption of the drying part increases.

[0209] Since the fibers are not separated, the amount of added amylase is also insufficient, which reduces the alcohol degree and increases the total energy consumption.

[0210] The solid content of the first and second clear liquids and the syrup and the viscosity of the syrup were measured, and the results are shown in Table 1. The water consumption, steam consumption and energy consumption per 1 t of ethanol (95% by volume) produced are shown in Table 2.

[0211] Comparative Example 2

[0212] This comparative example illustrates a reference method for producing ethanol co-product feed from wheat.

[0213] The system and method described in Example 1 were operated, except that the system did not contain an anaerobic unit, and 100% of the second clear liquid was subjected to evaporation treatment.

[0214] 0.65 kg of DDGS, 0.35 kg of protein feed and 0.15 kg of fiber feed were co-produced per 1 t of ethanol (95% by volume) produced.

[0215] The solid content of the first and second clear liquids and the syrup and the viscosity of the syrup were measured, and the results are shown in Table 1. The water consumption, steam consumption and energy consumption per 1 t of ethanol (95% by volume) produced are shown in Table 2.

[0216] Because the clear liquid was 100% sent to the evaporation unit, the energy consumption required for evaporation increased, and because the clear liquid was not sent to the IC unit, no steam was produced in the IC section, and the energy consumption of the steam increased. Because the clear liquid was not recycled, the slurry water needed to be supplemented with fresh process water, and the consumption of process water increased.

[0217] Comparative Example 3

[0218] This comparative example illustrates a reference method for producing ethanol co-product feed from wheat.

[0219] The system and method described in Example 1 were operated, except that the system did not contain a second separation unit, and the clear liquid from the first separation unit was all sent to the evaporation unit.

[0220] 0.85 kg of DDGS and 0.15 kg of fiber feed were co-produced per 1 t of ethanol (95% by volume) produced.

[0221] The solid content of the first and second clear liquids and the syrup and the viscosity of the syrup were measured, and the results are shown in Table 1. The water consumption, steam consumption and energy consumption per 1 t of ethanol (95% by volume) produced are shown in Table 2.

[0222] Since the clear liquor from the first separation unit has high solid content, the load of evaporation is high, the steam consumption is increased. Moreover, the amount of clear liquor is large, the evaporation cannot meet the load requirement, generally the efficiency is decreased by 50% (compared with the device using whole corn as raw material); and the viscosity of the syrup is high, the evaporation is easy to be blocked, the solid content of the syrup has to be decreased so as to reduce the viscosity. There is no protein feed production, and no steam produced by the IC part, the total steam consumption is increased. The clear liquor is not reused, the consumption of fresh water is increased.

[0223] Table 1

[0224]

[0225] Table 2

[0226] Number Water consumption t / t ethanol Steam consumption t / t ethanol Energy consumption MJ / t ethanol Example 1 5.0 3.8 14299 Comparative Example 1 4.9 4.3 16181 Comparative Example 2 6.3 5.1 19191 Comparative Example 3 6.7 5.3 19945

[0227] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that various technical features are combined in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all fall within the protection scope of the present application.

Claims

1. A system for producing ethanol and co-producing feed using wheat, characterized in that, In a method for producing ethanol from wheat, the wheat is used in an amount of 100% by weight. The system comprises: The grinding unit is used to grind wheat to obtain the ground product; The fiber washing unit washes the pulverized product to obtain fiber material and material to be slurried. The slurry preparation unit is used to prepare the material to be slurry to obtain starch slurry; A liquefaction unit is used to liquefy the starch slurry to obtain a liquefied liquid; A fermentation unit is used to ferment the liquefied liquid to obtain mature mash. A distillation unit is used to distill and separate the mature mash to obtain ethanol and waste mash. The first separation unit is used to perform a first separation on the waste mash to obtain a first clear liquid and a first wet cake; The second separation unit is used to perform a second separation on the first clear liquid to obtain a second clear liquid and a second wet cake. An anaerobic unit is used to anaerobically treat at least a portion of the second clear liquid to obtain anaerobically treated clear liquid and biogas, wherein the anaerobically treated second clear liquid accounts for 30-70% of the total volume of the second clear liquid; An evaporation unit is used to evaporate at least a portion of the second clear liquid to obtain syrup and evaporated condensate; The anaerobic unit is connected to the fiber washing unit and / or sizing unit via pipelines, and is used to circulate the clarified liquid after anaerobic treatment to the fiber washing unit and / or sizing unit as washing water and / or sizing water; and / or, The evaporation unit is also connected to the fiber washing unit and / or sizing unit via pipelines, for circulating the evaporated condensate to the fiber washing unit and / or sizing unit as washing water and / or sizing water. The drying unit, connected via pipelines to the first separation unit, the second separation unit, the fiber washing unit, and the evaporation unit, is used to dry the first wet cake to obtain DDGS; to dry the second wet cake and optional syrup to obtain protein feed; and to dry a mixture of fiber material and at least a portion of syrup to obtain fiber feed.

2. The system according to claim 1, wherein, The drying unit is also connected to the slurry conditioning unit and / or the anaerobic unit via pipelines, for circulating the dried condensate produced during drying to the slurry conditioning unit as slurry conditioning water, and / or circulating the dried condensate to the anaerobic unit for anaerobic treatment to obtain anaerobic clear liquid and biogas.

3. The system according to claim 1, wherein, The system also includes a steam generation unit for generating steam from the biogas to obtain biogas source steam; The biogas source steam serves as part of the heat source for the distillation unit and / or the drying unit.

4. A method for producing ethanol and co-producing feed using wheat, characterized in that, The method includes: (1) Wheat is crushed to obtain a crushed product, wherein the amount of wheat in the crushed product is 100% by weight; (2) The pulverized product is subjected to fiber washing to obtain fiber material and slurry material to be prepared; (3) The material to be mixed is mixed to obtain starch slurry; (4) The starch slurry is liquefied to obtain a liquefied liquid; (5) Ferment the liquefied liquid to obtain mature mash; (6) Distill the mature mash to obtain ethanol and waste mash; (7) The waste mash is first separated to obtain a first clear liquid and a first wet cake; (8) Perform a second separation on the first clear liquid to obtain a second clear liquid and a second wet cake; (9) At least a portion of the second clear liquid is subjected to anaerobic treatment to obtain anaerobic clear liquid and biogas, wherein the anaerobic treated second clear liquid accounts for 30-70% of the total volume of the second clear liquid; (10) Evaporate at least a portion of the second clear liquid to obtain syrup and evaporated condensate; The clarified liquid after anaerobic treatment and / or the evaporated condensate are recycled to the fiber washing step and / or sizing step as washing water and / or sizing water; and / or, The dried condensate produced in the drying step is recycled to the slurry preparation step as slurry preparation water, and / or the dried condensate is recycled to the anaerobic step for anaerobic treatment to obtain anaerobic clear liquid and biogas. (11) The first wet cake is dried to obtain DDGS; the second wet cake and optional syrup are dried to obtain protein feed; the mixture of fiber material and at least part of syrup is dried to obtain fiber feed.

5. The method according to claim 4, wherein, The pulverization conditions allow more than 80% by weight of the pulverized product to pass through a 20-mesh sieve.

6. The method according to claim 5, wherein, The conditions for preparing the starch slurry include: a temperature of 90-105℃, and a solids content of 20-40% by weight in the starch slurry; and / or The liquefaction conditions include: a temperature of 55-120℃; a pH of 3-8; a time of 0.2-10h; and / or The fermentation conditions include: pH value of 2-7; temperature of 25-40℃; and time of 2-5 days.

7. The method according to claim 4, wherein, The conditions for the first separation are such that the solid content in the first supernatant is 5-10% by weight; and / or The conditions for the second separation are such that the solid content in the second supernatant is less than 3.5% by weight.

8. The method according to claim 4, wherein, The method also includes steam generation of the biogas to obtain biogas source steam; The biogas source steam serves as part of the heat source for the distillation and / or drying steps.

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