System and method for producing cellulosic ethanol by saccharification and fermentation of biomass

Abstract

The present invention relates to a system for producing cellulosic ethanol by saccharification and fermentation of biomass, including a reactor A for an enzymatic decomposition reaction of a biomass feedstock, a reactor B for a fermentation reaction of the biomass feedstock, a storage tank for storing materials from the reactor B, and a collection tank for collecting cellulosic ethanol produced by the fermentation reaction of the biomass feedstock. The reactor A is connected to the reactor B, the storage tank, and the collection tank, respectively, and the reactor B is connected to the storage tank. The present invention also discloses a method for producing cellulosic ethanol using the system. The present invention effectively reduces the inhibition of enzymatic decomposition and fermentation caused by the accumulation of ethanol and improves the conversion rate of cellulosic ethanol by performing the cyclic processes of enzymatic decomposition saccharification, fermentation, and ethanol extraction on the biomass feedstock at intervals multiple times, and furthermore, by providing a storage tank, two batches of materials can be processed simultaneously in one system, greatly improving the production efficiency of cellulosic ethanol.

Description

[Technical field]

[0001] The present invention relates to the technical field of cellulosic ethanol production, and in particular to a system and method for producing cellulosic ethanol by saccharification and fermentation of biomass. [Background technology]

[0002] The development of sustainable and non-polluting energy is a trend in technological development, and agricultural production generates large amounts of lignocellulosic wastes every year, such as straw and corn cobs. Lignocellulosic materials are mainly composed of cellulose, hemicellulose, lignin and a small amount of ash. The cellulose components can be enzymatically decomposed and saccharified by cellulase to obtain glucose, which can be biofermented to produce cellulosic ethanol, a clean fuel.

[0003] At present, there are many bottlenecks in the process of producing cellulosic ethanol from biomass raw materials. The process of producing cellulosic ethanol mainly includes biomass pretreatment, cellulase enzymatic hydrolysis, and glucose fermentation. Among them, the cellulase enzymatic hydrolysis saccharification process has a difficult problem in that the product glucose inhibits the process of increasing the solid content of the enzymatic hydrolysis system, especially in the later stage of enzymatic hydrolysis, the released monomer glucose concentration increases, which further inhibits cellulase activity, which leads to a decrease in the overall enzymatic hydrolysis efficiency and a decrease in the conversion efficiency of cellulose enzymatic hydrolysis.

[0004] To overcome the problem of product inhibition in enzymatic hydrolysis, the currently most widely applied technology is synchronous saccharification and fermentation (SSF), which alleviates product inhibition by fermenting cellulosic ethanol by microorganisms during the process of glucose being enzymatically decomposed and released by cellulase. It combines the two processes of enzymatic decomposition by cellulase and glucose fermentation into one. However, there are some problems. The optimal reaction temperature of the currently common high-performance commercial cellulases is usually above 45°C, and the optimal fermentation temperature of the strains of common ethanol fermentation bacteria, such as Saccharomyces cerevisiae, is 35°C. At 45°C, the ethanol fermentation strains not only cannot grow and produce ethanol, but are also prone to apoptosis. The synchronous saccharification and fermentation process cannot achieve the optimal conditions for enzymatic decomposition saccharification and fermentation. In addition, the produced ethanol also has a certain inhibitory effect on cellulase, which affects both enzymatic decomposition and fermentation efficiency. Summary of the Invention [Problem to be solved by the invention]

[0005] The technical problem that the present invention aims to solve is to provide a system and method for producing cellulosic ethanol through saccharification and fermentation of biomass, which solves the problem of product glucose inhibiting cellulase protein activity by combining a cellulose enzymatic hydrolysis process and an ethanol fermentation process into an intermittent enzymatic hydrolysis and fermentation process, thereby improving the production of cellulosic ethanol. [Means for solving the problem]

[0006] The present invention is achieved as follows: A reactor A for an enzymatic decomposition reaction of a biomass feedstock, a reactor B for a fermentation reaction of the biomass feedstock, and a collection tank for collecting cellulosic ethanol produced by the fermentation reaction of the biomass feedstock, each of which is individually provided with an enzymatic decomposition supply pipe and a fermentation supply pipe, the outlet of the reactor A is connected to the inlet of the reactor B via a fermentation pipe provided therein, the fermentation pipe is provided with a diaphragm pump A, the outlet of the reactor B is connected to the inlet of the reactor A via a discharge pipe provided therein, and the discharge pipe is provided with a diaphragm pump B and a first discharge a first discharge pipe is provided behind a diaphragm pump B; the upper part of the reactor A is connected to an inlet of a collection tank via an provided ethanol piping; an insulation layer for heating and maintaining the temperature of the reactor A is provided outside the reactor A; a coil-type insulation device is provided at a connection site of the ethanol piping at the upper part of the reactor A; the coil-type insulation device and the insulation layer are each sequentially connected to a hot water tank via a provided hot water pipe; and a centrifugal pump is provided in the hot water pipe.

[0007] Specifically, the enzyme digestion feed pipe is used to add enzyme digestion materials such as enzyme digestible biomass feedstock, acid solution, and enzyme digestion feedstock into reactor A. The fermentation feed pipe is used to add fermentation materials such as fermentation strains into reactor B. Biomass feedstocks include straw and agricultural residues, and commonly used biomass feedstocks include corn stalks and leaves, corn cobs, bagasse, etc. The ethanol pipe is used to transport cellulosic ethanol vapor evaporated from the fermented biomass feedstock in reactor A.

[0008] Further, the discharge piping is further provided with a storage tank, a diaphragm pump C and a second discharge pipe, the storage tank being located after the first discharge pipe and used for storing the material from the reactor B, and the second discharge pipe being located after the diaphragm pump C.

[0009] The present invention is accomplished as follows: The above-mentioned cellulosic ethanol production system by saccharification and fermentation of biomass is used, Step 1: adding biomass raw material to a citrate buffer solution with a concentration of 0.1 mol / L and a pH of 5.0-6.0 with a content of 15%-20% on a dry basis, then adding cellulase accounting for 4%-6% on a dry basis, and adding the produced biomass raw material to reactor A through an enzyme digestion feed pipe; Step 2: maintaining the temperature of the reactor A at the enzyme decomposition reaction temperature T, maintaining the pH value of the material in the reactor A, and carrying out a first enzyme decomposition reaction on the material in the reactor A for 10 h to 14 h while stirring; Step 3: Send the material that has undergone the enzymatic decomposition reaction in the reactor A to the reactor B through the fermentation pipe, add 0.1% by mass to 1% by mass of the fermentation strain into the reactor B through the fermentation supply pipe, control the fermentation temperature to a fermentation temperature appropriate for the fermentation strain, and perform a first fermentation reaction on the material in the reactor B for 10 h to 14 h while stirring; Step 4: after the first fermentation reaction is completed, the material in the reactor B is sent to the reactor A through the discharge pipe, and the cellulosic ethanol produced by the fermentation of the material is evaporated in the reactor A into cellulosic ethanol vapor, and the cellulosic ethanol vapor is allowed to flow into the collection tank through the ethanol pipe to be condensed into cellulosic ethanol; and step 5, repeating steps 2, 3 and 4 to subject the batch of material to one cycle operation in each of reactor A and reactor B for 4 to 6 cycles, ending in reactor B, and finally discharging the batch of material from the system via a first discharge pipe.

[0010] The present invention achieves the following: The cellulosic ethanol production system by saccharification and fermentation of biomass is used, Step I: adding biomass raw material with a content of 15%-20% on a dry basis to a citrate buffer solution with a concentration of 0.1 mol / L, then adding cellulase with a content of 4%-6% on a dry basis, maintaining the pH of the citrate buffer solution at 5.0-6.0, and adding the first batch of material produced to reactor A through the enzyme digestion feed pipe; Step II: maintaining the temperature of the reactor A at the enzyme hydrolysis reaction temperature T, maintaining the pH value of the material, and carrying out the first enzyme hydrolysis reaction on the first batch of material in the reactor A for 10h to 14h while stirring; The first batch of materials that have undergone the enzymatic decomposition reaction in the reactor A are sent to the reactor B through the fermentation pipe, 0.1% by mass to 1% by mass of the fermentation strain is added to the reactor B through the fermentation supply pipe, the fermentation temperature is controlled to a fermentation temperature appropriate for the fermentation strain, and the first batch of materials in the reactor B is subjected to a first fermentation reaction for 10 hours to 14 hours while being stirred; After discharging all of the first batch of materials that have been subjected to the enzymatic decomposition reaction in the reactor A, step I and step II are repeated, a second batch of materials is added to the reactor A, and the second batch of materials is subjected to the enzymatic decomposition reaction in the reactor A. Step III. After the first fermentation reaction is completed, the first batch of materials in the reactor B is sent to a storage tank through a discharge pipe for temporary storage, and after the first batch of materials in the reactor B is completely discharged, step III is repeated to send the second batch of materials in the reactor A to the reactor B through a fermentation pipe for fermentation reaction in step IV; After discharging all of the second batch of materials from reactor A, it is temporarily stored in a storage tank, and the first batch of materials is sent to reactor A through a discharge pipe, and step II is further carried out, in which the cellulosic ethanol produced by fermentation of the first batch of materials is evaporated in reactor A into cellulosic ethanol vapor, and the cellulosic ethanol vapor is sent to a collection tank through an ethanol pipe to be condensed into cellulosic ethanol; After discharging all of the first batch of materials in the storage tank, step IV is repeated, and the second batch of materials in the reactor B is sent to the storage tank through the discharge pipe for temporary storage in step V; The present invention further provides a method for producing cellulosic ethanol, comprising: repeating steps II to V, performing two-cycle operation in reactor A and reactor B for 4 to 6 cycles for each of the two batches of material, and finishing each in reactor B; and finally, step VI, sequentially discharging the two batches of material from the system via a first discharge pipe. Effect of the Invention

[0011] Compared with the prior art, the system and method for producing cellulosic ethanol by saccharification and fermentation of biomass of the present invention has the following features: 1. In the process of enzymatic hydrolysis and fermentation of biomass raw materials with high solid content, the method of the present invention can use fermentation bacteria to ferment glucose to produce cellulosic ethanol after the enzymatic hydrolysis product, fermentable glucose, accumulates to a certain concentration, thereby solving the problem of cellulase activity inhibition caused by glucose accumulation.

[0012] 2. By integrating the cellulose enzymatic decomposition process, fermentation process and ethanol extraction process, and performing the enzymatic decomposition saccharification, fermentation and extracted ethanol circulation processes for each biomass raw material multiple times at intervals, the inhibition of enzymatic decomposition and fermentation caused by ethanol accumulation is reduced, and the conversion rate of cellulosic ethanol is improved. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the principle of a first structure of a system for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the principle of a second structure of the system for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention. [Diagram 3] FIG. 1 is a graph showing the time course of glucose release concentration in an enzymatic decomposition system to which glucose and ethanol were externally added. [Figure 4] This is a summary histogram of the survival rate at each temperature in a heat resistance test of Saccharomyces cerevisiae. [Diagram 5] 1 is a summary histogram of the survival rate at each temperature in a Zymomonas mobilis heat resistance test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In order to clarify the technical problems, technical solutions and advantageous effects of the present invention, the present invention will be described in more detail with reference to the drawings and examples below. Note that the specific examples described herein are merely for the purpose of interpreting the present invention and are not intended to limit the present invention.

[0015] Referring to Figure 1, a first embodiment of the system for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention is shown. The directions indicated by the arrows in the figure are the directions in which materials in the system, such as biomass feedstock, steam, refrigerated water, condensed water, bacteria, ethanol, etc., are transported. The system includes a reactor A1 for an enzymatic decomposition reaction of the biomass feedstock, a reactor B2 for a fermentation reaction of the biomass feedstock, and a collection tank 4 for collecting the cellulosic ethanol produced in the fermentation reaction of the biomass feedstock.

[0016] The reactor A1 and the reactor B2 are each provided with an enzyme decomposition supply pipe 11 and a fermentation supply pipe 21, and the outlet of the reactor A1 is connected to the inlet of the reactor B2 via the provided fermentation pipe 6. The fermentation pipe 6 is provided with a diaphragm pump A7, and the outlet of the reactor B2 is connected to the inlet of the reactor A1 via the provided discharge pipe 8. The discharge pipe 8 is provided with a diaphragm pump B9 and a first discharge pipe 16, and the first discharge pipe 16 is located behind the diaphragm pump B9. The upper part of the reactor A1 is connected to the inlet of the collection tank 4 via the provided ethanol pipe 10.

[0017] A heat-insulating layer 12 for heating and maintaining the temperature of the reactor A1 is provided outside the reactor A1, and a coil-type heat-insulating device 13 is provided at the connection portion of the ethanol pipe 10 at the top of the reactor A. The coil-type heat-insulating device 13 and the heat-insulating layer 12 are sequentially connected to the hot water tank 5 via the hot water pipe 14 provided therein, and a centrifugal pump 15 is provided on the hot water pipe 14. The coil-type heat-insulating device 13 is used to ensure that the cellulosic ethanol vapor evaporated in the reactor A1 is sent to the collection tank 4 without condensation. The hot water in the hot water tank 5 is fed by the centrifugal pump 15 into the coil-type heat-insulating device 13 at the top of the reactor A1 and the heat-insulating layer 12 outside the reactor A1 to control the temperature of the reactor A1 and the coil-type heat-insulating device 13.

[0018] An ethanol cooling device 19 for condensing cellulosic ethanol vapor is provided at the connection point of the ethanol pipe 10 at the top of the collection tank 4. The ethanol cooling device 19 facilitates condensation and collection of the cellulosic ethanol vapor passing through the ethanol pipe 10 with frozen water.

[0019] A fermentation and cooling device 20 for lowering the temperature of the fermentation material in the reactor B2 is provided outside the reactor B2.

[0020] A stirring device (not shown) is provided inside each of the reactor A1 and the reactor B2.

[0021] In this example, the batch of biomass material undergoes one cycle of flow between reactor A1 and reactor B2.

[0022] Referring to Figure 2, a second embodiment of the cellulosic ethanol production system by saccharification and fermentation of biomass according to the present invention is shown. Compared with the above embodiment, in this embodiment, the discharge pipe 8 is further provided with a storage tank 3, a diaphragm pump C17 and a second discharge pipe 18, the storage tank 3 is located after the first discharge pipe 16 and is used to store the material from the reactor B2, and the second discharge pipe 18 is located after the diaphragm pump C17. The other structures are similar to those of the first embodiment, so no further mention is made.

[0023] In this embodiment, since storage tank 3 is additionally installed as a temporary operation storage tank, the cellulosic ethanol production system by saccharification and fermentation of biomass of the present invention enables simultaneous operation of two batches of biomass material, and the two batches of biomass material are each sequentially subjected to two cycles of flow between reactor A1 and reactor B2.

[0024] The present invention further discloses a method for producing cellulosic ethanol by saccharification and fermentation of biomass, which employs the above-mentioned system for producing cellulosic ethanol by saccharification and fermentation of biomass and includes the following steps 1 to 5.

[0025] Step 1: Biomass raw material is added to a citrate buffer solution with a concentration of 0.1 mol / L and a pH of 5.0-6.0 at a content of 15%-20% (w / w) on a dry basis, and then cellulase is added at a concentration of 4%-6% (w / w) on a dry basis, and the produced biomass raw material is added to the reactor A1 via the enzyme hydrolysis supply pipe 11.

[0026] Step 2: Maintain the temperature of reactor A1 at the enzyme hydrolysis reaction temperature T, maintain the pH value of the material in reactor A, and perform the first enzyme hydrolysis reaction on the material in reactor A1 with stirring for 10 to 14 hours.

[0027] Step 3: The material that has undergone the enzymatic decomposition reaction in reactor A1 is sent to reactor B2 via fermentation piping 6, and 0.1% to 1% by mass of a fermentation strain is added to reactor B2 via fermentation supply pipe 21. The fermentation temperature is controlled to a fermentation temperature appropriate for the fermentation strain, and the material in reactor B2 is subjected to a first fermentation reaction for 10 to 14 hours while being stirred.

[0028] Step 4: After the first fermentation reaction is completed, the material in the reactor B2 is sent to the reactor A1 through the discharge pipe 8, and the cellulosic ethanol produced by the fermentation of the material is evaporated into cellulosic ethanol vapor in the reactor A, and the cellulosic ethanol vapor is allowed to flow into the collection tank through the ethanol pipe to be condensed into cellulosic ethanol.

[0029] Step 5: Repeat steps 2, 3 and 4, and perform 4 to 6 cycles of one cycle operation for the same batch of material in each of reactor A1 and reactor B2, and perform 4 to 6 times of enzymatic decomposition reaction and fermentation reaction, respectively, and terminate in reactor B2, and finally discharge the material from the system via the first discharge pipe 16.

[0030] The process is a one-cycle method for producing cellulosic ethanol by saccharification and fermentation of biomass.

[0031] The enzymatic decomposition reaction temperature T is the maximum temperature at which the survival rate of the fermentation bacteria is 80% or more. The enzymatic decomposition reaction temperature T is measured by preparing a test system using a 0.1 mol / L citric acid buffer solution, adding 100 g / L glucose and 1% by mass of the fermentation bacteria strain, incubating for 12 hours at 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, and 50°C, respectively, counting the number of viable bacteria of the fermentation bacteria strain using the plate count method, and determining the maximum temperature at which the survival rate of the viable bacteria after 12 hours is 80% as the enzymatic decomposition reaction temperature T.

[0032] The cellulase used in the enzymatic degradation reaction is Cellic CTec 2.

[0033] The present invention discloses another method for producing cellulosic ethanol by saccharification and fermentation of biomass. This production method uses the above-mentioned system for producing cellulosic ethanol by saccharification and fermentation of biomass, and includes the following steps I to V.

[0034] Step I: Biomass raw material is added to a citrate buffer solution with a concentration of 0.1 mol / L and pH of 5.0-6.0 at a content of 15%-20% (w / w) on a dry basis, then cellulase accounting for 4%-6% (w / w) on a dry basis is added, and the first batch of material produced is added to reactor A1 via enzyme digestion supply pipe 11.

[0035] Step II: Maintain the temperature of the reactor A1 at the enzyme hydrolysis reaction temperature T to maintain the pH value of the material, and carry out the first enzyme hydrolysis reaction on the first batch of material in the reactor A1 with stirring for 10 h to 14 h.

[0036] Step III: The first batch of materials that have undergone the enzymatic decomposition reaction in reactor A1 are sent to reactor B2 via fermentation piping 6, and 0.1% to 1% by mass of a fermentation strain is added to reactor B2 via fermentation supply pipe 21. The fermentation temperature is controlled to a fermentation temperature appropriate for the fermentation strain, and the first batch of materials in reactor B2 is subjected to a first fermentation reaction for 10 to 14 hours while being stirred.

[0037] After discharging all of the first batch of materials that have undergone the enzymatic decomposition reaction in reactor A1, steps I and II are repeated to add a second batch of materials to reactor A, and the second batch of materials is subjected to the enzymatic decomposition reaction in reactor A.

[0038] Step IV: After the first fermentation reaction is completed, the first batch of materials in the reactor B2 is sent to the storage tank 3 via the discharge pipe 8 for temporary storage, and after the first batch of materials in the reactor B2 is completely discharged, step III is repeated and the second batch of materials in the reactor A1 is sent to the reactor B2 via the fermentation pipe 6 for the fermentation reaction.

[0039] Step V: After discharging all of the second batch of materials from reactor A1, the first batch of materials temporarily stored in storage tank 3 is sent to reactor A1 through discharge piping 8, and step II is further carried out to evaporate the cellulosic ethanol produced by fermentation of the first batch of materials in reactor A into cellulosic ethanol vapor, and the cellulosic ethanol vapor is sent to a collection tank through ethanol piping to be condensed into cellulosic ethanol.

[0040] After the first batch of materials in the storage tank 3 has been completely discharged, step IV is repeated and the second batch of materials in the reactor B2 is sent to the storage tank 3 via the discharge pipe 8 for temporary storage.

[0041] Step VI: Repeat steps II to V, and perform 4 to 6 cycles of two-cycle operation in reactor A1 and reactor B2 for each of the two batches of material, perform the enzymatic decomposition reaction and the fermentation reaction 4 to 6 times each, and terminate them sequentially in reactor B2, and finally discharge the two batches of material sequentially from the system via the first discharge pipe 16.

[0042] The other steps are similar to the previous embodiment, so they will not be mentioned further.

[0043] The process is a two-cycle method for producing cellulosic ethanol by saccharification and fermentation of biomass.

[0044] The present systems and methods for producing cellulosic ethanol by saccharification and fermentation of biomass are further illustrated below with reference to specific examples. <Example 1> Experiment to verify the inhibitory effect of glucose and ethanol on enzymatic degradation

[0045] A reaction system was prepared using 0.1 mol / L citric acid buffer solution. The citric acid buffer solution was added to the corn cob residue system (15% (w / w) on a dry basis), the pH was maintained at 5.0-6.0, and cellulase Cellic CTec 2 (4% (w / w) on a dry basis) was added to prepare three 1 L reaction systems. [Table 1]

[0046] The enzyme hydrolysis was carried out at 50°C for 72 hours while stirring at 300 rpm, and samples were taken every 12 hours to measure the amount of glucose released by the enzyme hydrolysis. The results are shown in Figure 3.

[0047] Conclusion: Both glucose and ethanol have a certain inhibitory effect on the enzymatic decomposition of cellulase. In group B, after adding 100g / L glucose, the amount of glucose released by enzymatic decomposition for 72 hours was 24% lower than that of group A, the control group without inhibitors. In group C, after adding 50g / L ethanol, the amount of glucose released by enzymatic decomposition for 72 hours was 8% lower than that of group A, the control group. <Example 2> The enzyme decomposition reaction temperature T was confirmed through heat resistance experiments of Saccharomyces cerevisiae and Zymomonas mobilis manufactured by An Chi Co., Ltd.

[0048] The method of the present invention can be applied to many kinds of ethanol-fermenting bacterial strains. In this embodiment, two common ethanol-fermenting bacterial strains, Saccharomyces cerevisiae and Zymomonas mobilis, produced by An Chi Co., Ltd., are used as examples.

[0049] A 100g / L glucose solution was prepared using a citrate buffer solution, and divided into two portions. 1% by mass of Saccharomyces cerevisiae powder manufactured by An Chi Co., Ltd. and 1% by mass of Zymomonas mobilis liquid were added to each portion, and then samples were taken. Each was left at different temperatures in the range of 40℃ to 50℃ at 1℃ intervals, and incubated for 12 hours. The number of live bacteria was counted before and after incubation using the plate count method, and the change in the number of bacteria after incubation relative to the time of inoculation was statistically recorded. The statistical results are shown in Figures 4 and 5 below, respectively.

[0050] Conclusion: As a result of the tests and statistics, the highest temperature at which the survival rate after 12 hours of incubation is 80% or more is defined as the enzymatic decomposition reaction temperature T. The enzymatic decomposition reaction temperature T of An Chi's Saccharomyces cerevisiae is 45℃, and the enzymatic decomposition reaction temperature T of Zymomonas mobilis is 48℃. <Example 3> A first embodiment of one cycle of the method for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention includes the following steps (11) to (17).

[0051] Step (11): Since the enzymatic decomposition reaction temperature T was confirmed in Example 2, proceed directly to step (12).

[0052] Step (12): Preparation of reaction system materials A corn cob residue with a dry basis content of 15 kg (w / w) was added with an aqueous solution containing a citric acid buffer system up to 100 kg, the pH was maintained at 5.0-6.0, 0.6 kg of cellulase Cellic CTec 2 was added, and the reaction system material was added to the reactor A1 through the enzyme digestion supply pipe 11 after uniform stirring.

[0053] Step (13): The temperature of the reactor A1 was set to and maintained at 45°C, and the enzymatic hydrolysis reaction was carried out for 10 to 14 hours while stirring at 300 rpm.

[0054] Step (14): Set the temperature of reactor B2 to 35°C (optimal fermentation temperature of Saccharomyces cerevisiae), send the enzymatically decomposed material from reactor A1 to reactor B2 by diaphragm pump A7 in step (13), inoculate reactor B2 with 1 kg of An-Chi Saccharomyces cerevisiae powder from fermentation supply pipe 21, and perform fermentation reaction for 10 to 14 hours while stirring at 100 rpm, thereby completing one reaction cycle.

[0055] Step (15): The material fermented in step (14) was sent from reactor B2 to reactor A1, further stirred and subjected to a second enzymatic hydrolysis reaction, and the produced cellulosic ethanol was evaporated and collected in collection tank 4.

[0056] Step (16): The material that was subjected to the second enzymatic degradation in step (15) was further sent from reactor A1 to reactor B2.

[0057] Step (17): Steps (14) to (16) were repeated five times.

[0058] Finally, 4.4 kg of material is obtained in the collection tank 4, which contains 35% cellulosic ethanol, and 1.54 kg of cellulosic ethanol is obtained. 89.5 kg of material is obtained in the reactor B2, which contains 3.1% cellulosic ethanol, and 2.77 kg of cellulosic ethanol is obtained, and a total of 4.31 kg of cellulosic ethanol is obtained, and the conversion rate of cellulosic ethanol is calculated to be 84.5%. <Example 4> A second embodiment of one cycle of the method for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention includes the following steps (21) to (27).

[0059] Step (21): Since this is the same as in the third embodiment, proceed directly to step (22).

[0060] Step (22): Preparation of reaction system materials A corn cob residue having a dry basis content of 20 kg (w / w) was added with an aqueous solution containing a citric acid buffer system up to 100 kg, the pH was maintained at 5.0-6.0, 0.8 kg of cellulase Cellic CTec 2 was added, and the reaction system material was added to the reactor A1 through the enzyme decomposition supply pipe 11 after uniform stirring.

[0061] Step (23): The temperature of the reactor A1 was set to and maintained at 45°C, and the enzymatic hydrolysis reaction was carried out for 10 to 14 hours while stirring at 300 rpm.

[0062] Step (24): Set the temperature of reactor B2 to 35°C, and send the enzymatically decomposed material from reactor A1 to reactor B2 by diaphragm pump A7 in step (23). Inoculate reactor B2 with 1 kg of An-Chi Saccharomyces cerevisiae powder from fermentation supply pipe 21. Stir at 100 rpm to carry out fermentation reaction for 10 to 14 hours, thereby completing one reaction cycle.

[0063] Step (25): The fermented material from step (24) was sent from reactor B2 to reactor A1, further stirred and subjected to a second enzymatic hydrolysis reaction, and the produced cellulosic ethanol was evaporated and collected in collection tank 4.

[0064] Step (26): The material that was subjected to the second enzymatic degradation in step (25) was further sent from reactor A1 to reactor B2.

[0065] Step (27): Steps (24) to (26) were repeated for six cycles.

[0066] Finally, 4.7 kg of material is obtained in the collection tank 4, which contains 38% cellulosic ethanol, and 1.79 kg of cellulosic ethanol is obtained, and 90.5 kg of material is obtained in the reactor B2, which contains 4.1% cellulosic ethanol, and 3.71 kg of cellulosic ethanol is obtained, and a total of 5.50 kg of cellulosic ethanol is obtained, and the conversion rate of cellulosic ethanol is calculated to be 80.9%. <Example 5> A third embodiment of one cycle of the method for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention includes the following steps (31) to (37).

[0067] Step (31): Since this is the same as in the third embodiment, proceed directly to step (32).

[0068] Step (32): Preparation of reaction system materials To corn cob residue with a dry basis content of 20 kg (w / w), an aqueous solution containing a citric acid buffer system was added up to 100 kg, the pH was maintained at 5.0-6.0, 0.8 kg of cellulase Cellic CTec 2 was added, and the mixture was stirred uniformly. The obtained material was added to reactor A1 as a reaction system through enzyme digestion supply pipe 11.

[0069] Step (33): The temperature of the reactor A1 was set to and maintained at 48°C, and the enzymatic hydrolysis reaction was carried out for 10 to 14 hours while stirring at 300 rpm.

[0070] Step (34): The temperature of the reactor B2 is set to 35°C, and the enzymatically decomposed material in step (33) is sent from the reactor A1 to the reactor B2 by the diaphragm pump A7. 1 kg of activated Zymomonas mobilis liquid is inoculated into the reactor B2 through the fermentation supply pipe 21 of the reactor B2. The fermentation reaction is carried out for 10 to 14 hours while stirring at 100 rpm, thereby completing one reaction cycle.

[0071] Step (35): The fermented material from step (34) was sent from reactor B2 to reactor A1, further stirred and subjected to a second enzymatic hydrolysis reaction, and the produced cellulosic ethanol was evaporated and collected in collection tank 4.

[0072] Step (36): The material that was subjected to the second enzymatic degradation in step (35) was further sent from reactor A1 to reactor B2.

[0073] Step (37): Steps (34) to (36) were repeated for six cycles.

[0074] Finally, 4.8 kg of material is obtained in collection tank 4, which contains 39% cellulosic ethanol, and 1.87 kg of cellulosic ethanol is obtained; 93.5 kg of material is obtained in reactor B, which contains 4.13% cellulosic ethanol, and 3.86 kg of cellulosic ethanol is obtained, and a total of 5.73 kg of cellulosic ethanol is obtained, and the conversion rate of cellulosic ethanol is calculated to be 84.3%. <Example 6>

[0075] A first embodiment of the two-cycle method for producing cellulosic ethanol by saccharification and fermentation of biomass according to the present invention includes the following steps (41) to (48).

[0076] Step (41): Since this is the same as in the third embodiment, proceed directly to step (42).

[0077] Step (42): Producing a first batch of reaction system materials A corn cob residue with a dry basis content of 20 kg (w / w) was added with an aqueous solution containing a citric acid buffer system up to 100 kg, the pH was maintained at 5.0-6.0, 0.8 kg of cellulase Cellic CTec 2 was added, and the mixture was stirred uniformly to obtain a first batch of reaction system materials, and the first batch of reaction system materials was added to the reactor A1 through the enzyme hydrolysis supply pipe 11.

[0078] Step (43): The temperature of the reactor A1 was set to and maintained at 45°C, and the enzymatic hydrolysis reaction was carried out for 10 to 14 hours while stirring at 300 rpm.

[0079] Step (44): Set the temperature of the reactor B2 to 35°C, and send the first batch of materials enzymatically decomposed in step (43) from the reactor A1 to the reactor B2 by the diaphragm pump A7. Inoculate the reactor B2 with 1 kg of An-Chi Saccharomyces cerevisiae powder from the fermentation supply pipe 21 of the reactor B2, and carry out the fermentation reaction for 10 to 14 hours while stirring at 100 rpm, thereby completing one reaction cycle of the first batch of materials.

[0080] After all of the first batch of materials was sent from reactor A1 to reactor B2 by diaphragm pump A7, a second batch of reaction materials was produced according to the production method of step (42), and the second batch of reaction materials was treated as in step (43), that is, the second batch of materials produced in step (42) was sent to reactor A1 via enzyme decomposition supply pipe 11, and the enzyme decomposition reaction was carried out for 10 to 14 hours while stirring at 300 rpm.

[0081] Step (45): The first batch of materials in the reactor B2 is pumped to the storage tank 3 by the diaphragm pump B9, and then the second batch of materials in the reactor A1 is pumped to the reactor B2 and operated according to step (44), thereby completing one reaction cycle of the second batch of materials.

[0082] Step (46): The first batch of material in the storage tank 3 is sent to the reactor A1 through the discharge pipe 8, and further stirred and reacted. The produced cellulosic ethanol is evaporated and collected in the collection tank 4, and the second batch of material is sent from the reactor B2 to the storage tank 3.

[0083] Step (47): The first batch of materials is sent again from reactor A1 to reactor B2. The second batch of materials is always one vessel slower than the first batch of materials.

[0084] Step (48): Steps (44) to (46) were repeated for six cycles.

[0085] Finally, 8.8 kg of material is obtained in collection tank 4, which contains 38.5% cellulosic ethanol, and 3.39 kg of cellulosic ethanol is obtained, and two batches of material are discharged in total of 178.5 kg, which contains 4.2% cellulosic ethanol, and 7.50 kg of cellulosic ethanol is obtained, and a total of 10.85 kg of cellulosic ethanol is obtained, and the conversion rate of cellulosic ethanol is calculated to be 80.1%. <Example 7>

[0086] Comparison of the enzymatic decomposition effects between the method of the present invention and the synchronous saccharification and fermentation process

[0087] The data from Examples 4 and 5 were collected to statistically demonstrate the ethanol conversion rate during enzymatic hydrolysis and fermentation of 20% dry basis corn cob residue by the method of the present invention.

[0088] Conventional synchronous saccharification and fermentation: 100 kg of aqueous solution containing citric acid buffer was added to corn cob residue with a dry basis content of 20 kg (w / w), and the pH was maintained at 5.0-6.0. 0.8 kg of cellulase Cellic CTec 2 was added and stirred uniformly. 1 kg of An Chi yeast powder was inoculated and reacted for 6 days at 35°C and 300 rpm to obtain 100.5 kg of material, in which the cellulosic ethanol content was 5.2%. The conversion rate of cellulosic ethanol was calculated to be 76.9%.

[0089] Compared with the conventional synchronous saccharification and fermentation process, the conversion rate of cellulosic ethanol in the method of the present invention is improved from 76.9% to more than 80%, and the effect is obvious.

[0090] The above is merely a preferred embodiment of the present invention, and is not intended to limit the present invention. All modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principles of the present invention are intended to be included in the patent scope of the present invention.

Claims

1. A system for producing cellulosic ethanol by saccharification and fermentation of biomass, comprising: The present invention includes a reactor A for an enzymatic decomposition reaction of a biomass feedstock, a reactor B for a fermentation reaction of the biomass feedstock, and a collection tank for collecting cellulosic ethanol produced by the fermentation reaction of the biomass feedstock, and an enzymatic decomposition supply pipe and a fermentation supply pipe are individually provided for each of the reactor A and the enzymatic decomposition supply pipe are used to add an enzymatic decomposition material to the reactor A, and the fermentation supply pipe is used to add a fermentation material to the reactor B, the outlet of the reactor A is connected to the inlet of the reactor B via a fermentation piping provided therein, the fermentation piping is provided with a diaphragm pump A, and the outlet of the reactor B is connected to the inlet of the reactor B via a discharge piping provided therein. a diaphragm pump B and a first discharge pipe are provided in the discharge piping, the first discharge pipe is located behind the diaphragm pump B, an upper part of the reactor A is connected to the inlet of the collection tank via an provided ethanol piping, an insulation layer for raising the temperature of the reactor A and keeping the temperature of the reactor A is provided outside the reactor A, a coil-type insulation device is provided at a connection portion of the ethanol piping at the upper part of the reactor A, the coil-type insulation device and the insulation layer are each sequentially connected to a hot water tank via a provided hot water pipe, and a centrifugal pump is provided in the hot water pipe.

2. 2. The system for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 1, characterized in that the discharge piping is further provided with a storage tank, a diaphragm pump C and a second discharge pipe, the storage tank being located after the first discharge pipe and used for storing material from the reactor B, and the second discharge pipe being located after the diaphragm pump C.

3. 3. The system for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 1 or 2, characterized in that an ethanol cooling device for condensing cellulosic ethanol vapor is provided at the connection site of the ethanol piping at the top of the collection tank.

4. 3. The system for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 1 or 2, characterized in that a fermentation cooling device for lowering the temperature of the fermentation material in the reactor B is provided outside the reactor B.

5. 3. The system for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 1 or 2, wherein an agitator is provided inside each of the reactor A and the reactor B.

6. A method for producing cellulosic ethanol by saccharification and fermentation of biomass, comprising using a system for producing cellulosic ethanol by saccharification and fermentation of biomass according to any one of claims 1 to 5, Step 1: adding biomass raw material to a citrate buffer solution having a concentration of 0.1 mol / L and a pH of 5.0-6.0 with a content of 15%-20% on a dry basis, then adding cellulase accounting for 4%-6% on a dry basis, and adding the produced biomass raw material to a reactor A through an enzyme digestion supply pipe; Step 2: maintaining the temperature of the reactor A at an enzyme decomposition reaction temperature T to maintain the pH value of the material in the reactor A, and carrying out a first enzyme decomposition reaction on the material in the reactor A for 10 h to 14 h while stirring; Step 3: Send the material that has been subjected to the enzymatic decomposition reaction in the reactor A to the reactor B through the fermentation pipe, add 0.1% by mass to 1% by mass of the fermentation strain into the reactor B through the fermentation supply pipe, control the fermentation temperature to a fermentation temperature appropriate for the fermentation strain, and perform a first fermentation reaction on the material in the reactor B for 10 h to 14 h while stirring; Step 4: after the first fermentation reaction is completed, the material in the reactor B is sent to the reactor A through the discharge pipe, and the cellulosic ethanol produced by the fermentation of the material is evaporated in the reactor A into cellulosic ethanol vapor, and the cellulosic ethanol vapor is allowed to flow into the collection tank through the ethanol pipe and condensed into cellulosic ethanol; and step 5, repeating steps 2, 3, and 4 to perform one cycle of operation of the batch of material in each of reactor A and reactor B for 4 to 6 cycles, ending with reactor B, and finally discharging the batch of material from the system via a first discharge pipe.

7. 1. A method for producing cellulosic ethanol by saccharification and fermentation of biomass, comprising: The system for producing cellulosic ethanol by saccharification and fermentation of biomass according to any one of claims 2 to 5 is used, Step I: adding biomass raw material with a content of 15%-20% on a dry basis to a citrate buffer solution with a concentration of 0.1 mol / L, then adding cellulase with a content of 4%-6% on a dry basis, maintaining the pH of the citrate buffer solution at 5.0-6.0, and adding the first batch of material produced to reactor A through an enzyme digestion feed pipe; Step II: maintaining the temperature of the reactor A at an enzyme decomposition reaction temperature T to maintain the pH value of the material, and carrying out a first enzyme decomposition reaction on the first batch of material in the reactor A for 10h to 14h while stirring; The first batch of materials that have been subjected to the enzymatic decomposition reaction in the reactor A are sent to the reactor B through the fermentation pipe, 0.1% by mass to 1% by mass of the fermentation strain is added to the reactor B through the fermentation supply pipe, the fermentation temperature is controlled to a fermentation temperature appropriate for the fermentation strain, and the first batch of materials in the reactor B is subjected to a first fermentation reaction for 10 h to 14 h while being stirred; After discharging all of the first batch of materials that have been subjected to the enzymatic decomposition reaction in the reactor A, step I and step II are repeated, a second batch of materials is added to the reactor A, and the second batch of materials is subjected to the enzymatic decomposition reaction in the reactor A; and step III. After the first fermentation reaction is completed, the first batch of materials in the reactor B is sent to a storage tank through a discharge pipe for temporary storage, and after the first batch of materials in the reactor B is completely discharged, step III is repeated to send the second batch of materials in the reactor A through a fermentation pipe to the reactor B for fermentation reaction; and step IV. After the second batch of materials in the reactor A is completely discharged, it is temporarily stored in a storage tank, and the first batch of materials is sent to the reactor A through a discharge pipe, and step II is further carried out, in which the cellulosic ethanol produced by the fermentation of the first batch of materials is evaporated in the reactor A into cellulosic ethanol vapor, and the cellulosic ethanol vapor is sent to a collection tank through an ethanol pipe to be condensed into cellulosic ethanol; After discharging all of the first batch of materials in the storage tank, step IV is repeated, and the second batch of materials in the reactor B is sent to the storage tank through a discharge pipe for temporary storage in step V; and step VI, in which steps II to V are repeated to perform 4 to 6 cycles of two-cycle operation in reactor A and reactor B for each of the two batches of material, and then terminate the operation in reactor B, and finally, the two batches of material are sequentially discharged from the system via a first discharge pipe.

8. 8. The method for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 6 or 7, wherein the enzymatic decomposition reaction temperature T is the maximum temperature at which the survival rate of the fermentation bacteria species is 80% or more.

9. 8. The method for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 6 or 7, characterized in that the enzymatic decomposition reaction temperature T is measured by a method in which a test system is set up using a 0.1 mol / L citric acid buffer solution, 100 g / L glucose and 1 mass% fermentation strain are added thereto, and the test system is incubated for 12 hours under conditions of 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, and 50°C, respectively, and the number of viable bacteria of the fermentation strain is counted using a plate count method. The enzymatic decomposition reaction temperature T is determined by determining the maximum temperature at which the viable bacteria survival rate after 12 hours is 80%.

10. The method for producing cellulosic ethanol by saccharification and fermentation of biomass according to claim 6 or 7, characterized in that the cellulase used in the enzymatic degradation reaction is Cellic CTec 2.

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