Improved method for semi-continuous fermentation of ethanol

Abstract

The present invention relates to the field of ethanol fermentation, and discloses an improved method for a semi-continuous fermentation ethanol production process. The fermentation system for semi-continuous fermentation comprises a continuous fermentation section and an intermittent fermentation section connected in series, wherein the continuous fermentation section comprises a continuous fermentation production line connected in parallel, and the intermittent fermentation section comprises an intermittent fermentation tank connected in parallel; the method comprises: adding at least one continuous fermentation production line, and increasing the cleaning frequency of each continuous fermentation production line to 3-10 days / time. The present invention can effectively reduce the risk of bacterial contamination by increasing the number of continuous fermentation production lines and the cleaning frequency, and has better fermentation indicators, lower acid value, less antibacterial agent usage, and significant economic benefits.

Description

Technical Field

[0001] The invention relates to the field of ethanol fermentation, and in particular to an improved method for a semi-continuous fermentation ethanol production process. Background Art

[0002] Fuel ethanol production technology can be divided into intermittent fermentation technology and continuous fermentation technology according to different fermentation methods. Among them, the continuous fermentation technology can be divided into full continuous fermentation technology and semi-continuous fermentation technology. In 2020, my country's total fuel ethanol production capacity is 6 million tons, of which about 3 million tons are produced by continuous fermentation technology, accounting for about 50% of the total production capacity.

[0003] Although the continuous fermentation process can save investment, has a high degree of automation, and saves labor, it faces the problem of easy contamination. Unlike the intermittent fermentation process, which cleans each tank immediately after completion, the continuous fermentation process will try to avoid high-frequency cleaning because stopping production to clean the production line will affect production capacity. The continuous fermentation production line is often cleaned every few weeks, months, or even half a year. Therefore, compared with the intermittent fermentation process, the problem of contamination is more prominent, the amount of antibacterial agent used is larger, and the fermentation effect is poor. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of prominent bacterial contamination in semi-continuous fermentation, large dosage of antibacterial agents and poor fermentation effect in the prior art, and to provide an improved method for a semi-continuous fermentation ethanol production process. After the semi-continuous fermentation process is improved by this method, the risk of bacterial contamination can be effectively reduced without affecting the production efficiency, the fermentation effect is better, the acid value is lower, the dosage of antibacterial agents is better, and the alcohol content in the fermented mature mash can also be increased.

[0005] In order to achieve the above-mentioned purpose, the present invention provides an improved method for a semi-continuous fermentation ethanol production process, wherein the fermentation system for semi-continuous fermentation comprises a continuous fermentation section and an intermittent fermentation section connected in series, wherein the continuous fermentation section comprises a continuous fermentation production line connected in parallel, and the intermittent fermentation section comprises an intermittent fermentation tank connected in parallel; the method comprises: adding at least one continuous fermentation production line, and increasing the cleaning frequency of each continuous fermentation production line to 3-10 days / time.

[0006] Preferably, the total number of the continuous fermenters and the batch fermenters remains unchanged.

[0007] The present invention can effectively reduce the risk of bacterial contamination by increasing the number of continuous fermentation production lines and the cleaning frequency, and has better fermentation indicators, lower acid value, less antibacterial agent usage, and significant economic benefits.

[0008] In the preferred scheme, without changing the number of fermentation tanks and production efficiency of the original device, the chance of contamination is reduced by modifying the continuous fermentation line and increasing the cleaning frequency, thereby improving the quality of the mature mash, increasing the alcohol content, reducing the volatile acid content, and reducing the amount of antibacterial agents used. The improved process is suitable for concentrated mash fermentation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the traditional semi-continuous fermentation process;

[0010] Figure 2 is a schematic diagram of the semi-continuous fermentation process described in Example 1 of the present invention;

[0011] Figure 3 Schematic diagram of the semi-continuous fermentation process described in Example 4 of the present invention.

[0012] Description of Reference Numerals

[0013] A1-A3, B1-B3, C1-C3 and D1-D3 are continuous fermenters respectively; A4-A5, B4-B5 and C4-C5 are intermittent fermenters respectively. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] The present invention provides an improved method for a semi-continuous fermentation ethanol production process. The fermentation system used for the semi-continuous fermentation comprises a continuous fermentation section and an intermittent fermentation section connected in series, wherein the continuous fermentation section comprises a continuous fermentation production line connected in parallel, and the intermittent fermentation section comprises an intermittent fermentation tank connected in parallel; the method comprises: adding at least one continuous fermentation production line, and increasing the cleaning frequency of each continuous fermentation production line to 3-10 days / time.

[0016] Unless otherwise specified, the continuous fermentation production line, continuous fermentation tank and intermittent fermentation tank as well as related methods and parameters are descriptions of the improved process.

[0017] In the present invention, in the semi-continuous fermentation ethanol production process, the number of continuous fermentation production lines is not particularly limited, and the number can be set according to the production scale. Preferably, the continuous fermentation section includes at least three continuous fermentation production lines. That is, the continuous fermentation section in the process before improvement includes at least two continuous fermentation production lines.

[0018] In the present invention, the number of continuous fermentation stages, i.e., the number of continuous fermentation tanks connected in series in each continuous fermentation production line, can be selected within a wide range. In the art, the number of continuous fermentation stages of a device using semi-continuous fermentation is generally 1-5, more commonly 2-4; preferably, the continuous fermentation production line comprises at least two continuous fermentation tanks connected in series, more preferably 2 or 3 continuous fermentation tanks connected in series.

[0019] In the present invention, the number of intermittent fermentation tanks can be selected within a wide range, as long as the normal operation of the semi-continuous fermentation ethanol production process can be achieved.

[0020] In a preferred embodiment of the present invention, the method further comprises: while keeping the number of continuous fermentation tanks on each continuous fermentation production line unchanged, reducing the number of intermittent fermentation tanks. For example, the intermittent fermentation tanks can be converted into continuous fermentation tanks to form a new continuous fermentation production line. Specifically, for example, an ethanol fermentation system comprising 15 fermentation tanks is improved, the system comprises 3 continuous fermentation production lines connected in parallel (each production line comprises 3 continuous fermentation tanks) and 6 intermittent fermentation tanks connected in parallel, by converting 3 intermittent fermentation tanks into continuous fermentation tanks, and connecting them to form a new continuous fermentation production line in parallel with the other 3 continuous fermentation production lines. That is, the improved fermentation system comprises 4 continuous fermentation production lines connected in parallel (each production line comprises 3 continuous fermentation tanks) and 3 intermittent fermentation tanks connected in parallel.

[0021] In the present invention, preferably, the total number of the continuous fermentation tanks and the batch fermentation tanks remains unchanged.

[0022] In this preferred embodiment, in order to ensure that the fermentation capacity remains unchanged, it can be achieved by controlling the total material feed flow rate to remain unchanged and the total fermentation time to remain unchanged. When adding a continuous fermentation production line, the residence time of the material in the continuous fermentation tank can be increased, thereby shortening the residence time of the material in the intermittent fermentation tank, so that the time requirement of semi-continuous fermentation production can still be met when the number of intermittent fermentation tanks is reduced.

[0023] In a preferred embodiment of the present invention, the method further comprises: reducing the number of continuous fermentation tanks on each continuous fermentation production line and optionally increasing the number of intermittent fermentation tanks. For example, the reduced continuous fermentation tanks can be connected to form a new continuous fermentation production line by changing the pipeline, and the extra continuous fermentation tanks can be converted into intermittent fermentation tanks. Specifically, for example, an ethanol fermentation system comprising 15 fermentation tanks is improved, the system contains 3 continuous fermentation production lines connected in parallel (each production line contains 3 continuous fermentation tanks) and 6 intermittent fermentation tanks connected in parallel, by changing the continuous fermentation tanks in each continuous fermentation production line to 2, and connecting two of the continuous fermentation tanks to form a new continuous fermentation production line in parallel with the other 3 continuous fermentation production lines, and the remaining 1 continuous fermentation tank is converted into an intermittent fermentation tank. That is, the fermentation system after the transformation contains 4 continuous fermentation production lines connected in parallel (each production line contains 2 continuous fermentation tanks) and 4 intermittent fermentation tanks connected in parallel.

[0024] In this preferred embodiment, in order to ensure that the fermentation capacity remains unchanged, it can be achieved by controlling the total material feed flow rate to remain unchanged and the total fermentation time to remain unchanged. In the case of adding a continuous fermentation production line, the residence time of the materials in the continuous fermentation tank and the intermittent fermentation tank can be increased, so that the time requirement of semi-continuous fermentation production can still be met when the number of continuous fermentation tanks is reduced.

[0025] That is, in a preferred embodiment of the present invention, the method further comprises: increasing the residence time of the material in the continuous fermentation tank.

[0026] Preferably, the residence time of the material in each of the continuous fermentation tanks is 12-20 hours.

[0027] Preferably, the residence time of the material in each batch fermentation tank is 4-40h.

[0028] Preferably, the fermentation time of the semi-continuous fermentation is 60-72 hours.

[0029] Wherein, the residence time is the fermentation time of the corresponding stage.

[0030] In the present invention, the continuous fermentation tank can be equipped with conventional structures, devices and equipment capable of realizing continuous fermentation, and those skilled in the art can select a suitable connection method as needed. For example, the continuous fermentation tank can be provided with a stirring device, a CO2 discharge pipeline and an emergency pressure relief manhole, a CIP automatic cleaning device and a manual cleaning hole, etc. The continuous fermentation tank can also be provided with a heat exchange device (for example, a plate heat exchanger) inside or outside the tank.

[0031] Among them, the CIP automatic cleaning device can include, for example, at least 2 nozzles, such as 3 nozzles (each nozzle is installed at an angle of 120°), and there is no special restriction on the installation method, as long as the fermentation tank can be cleaned as cleanly as possible (preferably full coverage cleaning without dead angles).

[0032] In the present invention, cleaning can be performed under the control of a CIP automatic cleaning system. The CIP automatic cleaning system can include conventional equipment and devices, which will not be described in detail here.

[0033] The continuous fermentation tank may also be equipped with a circulation pump and a discharge pump. Valves may be provided before and after the pump to control the flow and flow rate of the material. The valves may be butterfly valves or stop valves.

[0034] In the present invention, the intermittent fermentation tank can be equipped with conventional structures, devices and equipment that can realize continuous fermentation, and those skilled in the art can select a suitable connection method as needed. For example, the intermittent fermentation tank can be provided with a stirring device, a CO2 discharge pipeline and an emergency pressure relief manhole, a CIP automatic cleaning device and a manual cleaning hole, etc. The intermittent fermentation tank can also be provided with a heat exchange device (for example, a plate heat exchanger) inside or outside the tank. The intermittent fermentation tank can also be provided with an intermittent fermentation tank pump, and valves can be provided before and after the pump to control the flow and flow rate of the material, and the valve can be a butterfly valve or a stop valve.

[0035] The fermentation method can be a conventional method in the art, for example, the yeast and saccharification mash can be pumped into a continuous fermentation production line in a certain ratio, and the materials flow through the continuous fermentation tank in sequence and then enter the intermittent fermentation tank. The inoculation ratio during the fermentation process is 25-75% by volume, that is, the flow rate ratio of the yeast and saccharification mash per unit time is 1:0.3-3.

[0036] The yeast can be prepared in a conventional manner in the art. Preferably, the number of live yeast cells in the yeast is 10 9 cuf / mL or above.

[0037] Preferably, the dry matter content in the saccharified mash is 20-34% by weight.

[0038] In the present invention, in order to inhibit bacterial contamination during the fermentation process, an antibacterial agent can be added during the fermentation process. The antibacterial agent can be a conventional antibacterial agent in the art, such as Anjuntai. Those skilled in the art can add the antibacterial agent according to actual needs, for example, the amount of the antibacterial agent added can be 0.002-0.02 volume‰.

[0039] Preferably, the continuous fermentation production line cleaning method includes: cleaning one continuous fermentation production line at a time; during the cleaning process of each continuous fermentation production line, cleaning is carried out in sequence from front to back along the direction of the material. For example, taking a continuous fermentation production line containing 3 continuous fermentation tanks as an example, the cleaning method may include gradually stopping the feeding of A1's yeast and saccharified mash (for example, the original feeding of 110m 3 / h, gradually reduce to 90m 3 / h,70m 3 / h,50m 3 / h,30m 3 / h until it stops), then discharge A1 to A2, empty A1 for 10h and turn off A1 discharge pump, and immediately perform CIP online cleaning on A1. After A1 is washed, open A1 feed valve to continue feeding, and at the same time, A2 discharges to A3 for 10h to empty A2, and turn off A2 discharge pump. After A2 is emptied, perform CIP online cleaning immediately. After A2 is cleaned, wait for A1 to be full, open A1 discharge pump to feed A2. After A2 is cleaned, A3 is discharged to the intermittent fermentation tank, cleaned, and fed again in the same way.

[0040] Preferably, the method for cleaning the intermittent fermentation tank comprises: cleaning the intermittent fermentation tank after each intermittent fermentation.

[0041] The specific cleaning method can be a conventional cleaning method in the art, such as first using alkali washing (the alkali solution can be, for example, a sodium hydroxide solution with a concentration of 2-6 wt %), and then using hot water (such as water with a temperature of more than 75° C.) for washing.

[0042] The present invention will be described in detail below through examples.

[0043] In the following examples and comparative examples, the production scale of ethanol is 300,000 tons, and the volume of each fermentation tank is 2000m 3 The total flow rate of materials entering the fermentation system per unit time remains unchanged, and the total flow rate is 330m 3 / h. Anjuntai was added as an antibacterial agent during the fermentation process.

[0044] The schematic diagram of the fermentation system before improvement is as follows Figure 1 As shown, the system includes three continuous fermentation production lines A, B and C connected in parallel, wherein Line A includes three continuous fermentation tanks A1, A2 and A3 connected in series in sequence, Line B includes three continuous fermentation tanks B1, B2 and B3 connected in series in sequence, Line C includes three continuous fermentation tanks C1, C2 and C3 connected in series in sequence, and there are 6 intermittent fermentation tanks A4, A5, B4, B5, C4 and C5 connected in parallel.

[0045] Each fermentation tank in the fermentation system is connected to the CIP automatic cleaning system for online cleaning. The CIP cleaning device in each fermentation tank includes 3 nozzles, which are installed at an angle of 120° to achieve 360° cleaning without dead ends. First, it is sprayed with 4 wt% sodium hydroxide solution for 8 minutes to discharge the sewage, and then sprayed with 85°C hot water for 20 minutes. After washing, it is discharged into the tank behind.

[0046] Example 1

[0047] This example is used to illustrate the method of ethanol fermentation.

[0048] based on Figure 1 The fermentation system connection mode shown in the figure is improved, and the original three intermittent fermentation tanks C4, B4 and A4 are respectively changed into three continuous fermentation tanks D1, D2 and D3, and connected in series to obtain a new continuous fermentation production line D line, forming 4 continuous lines including A line, B line, C line and D line, and the original three intermittent fermentation tanks A5, B5 and C5 remain unchanged. The fermentation system after the transformation contains 12 continuous fermentation tanks and 3 intermittent fermentation tanks, such as Figure 2 shown.

[0049] The saccharification mash (brown rice raw material) with a distiller's yeast and dry matter content of 30.5% by weight was pumped into A1 at an inoculation ratio of 50%. After A1 was filled with feed for 16 hours, it began to pump feed to A2. After A2 was filled with feed for 16 hours, it pumped feed to A3. A3 was filled with feed for 16 hours. Line B, line C, and line D were carried out in the same way. After A3, B3, C3, and D3 were filled with feed, the materials were mixed into a pipeline and pumped into intermittent fermentation tanks A5, B5, and C5 in turn for intermittent fermentation. The intermittent fermentation lasted for 18 hours. The materials after intermittent fermentation were pumped into a mature mash tank to obtain a mature mash. Anjuntai was added during the fermentation process, and the addition amount of Anjuntai was about 0.002 volume‰.

[0050] Clean one line every 4 days. First, gradually stop feeding A1 with yeast and mash, then discharge A1 to A2, empty A1 for 10 hours and turn off A1 discharge pump, and immediately perform CIP online cleaning on A1. After A1 is washed, open A1 feed valve to continue feeding, while A2 discharges to A3 for 10 hours to empty A2, and turn off A2 discharge pump. After A2 is emptied, perform CIP online cleaning immediately. After A2 is cleaned, wait for A1 to be full, and turn on A1 discharge pump to feed A2. After A2 is cleaned, A3 is discharged to the intermittent fermentation tank, cleaned, and then fed in the same way. The cleaning method of B, C and D lines is the same as that of A line. Each intermittent fermentation tank is fermented independently, and CIP online cleaning is performed after emptying and then feeding.

[0051] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0052] Example 2

[0053] This example is used to illustrate the method of ethanol fermentation.

[0054] Ethanol fermentation was carried out in the fermentation system described in Example 1, except that the dry matter content of the saccharified mash was 27.0 wt %.

[0055] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0056] Example 3

[0057] This example is used to illustrate the method of ethanol fermentation.

[0058] The method described in Example 2 is used for the operation, except that the saccharification mash is prepared using corn as raw material, and the dry matter content of the saccharification mash is 27% by weight.

[0059] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0060] Example 4

[0061] This example is used to illustrate the method of ethanol fermentation.

[0062] based on Figure 1 The fermentation system connection mode shown in the figure is improved, the original two intermittent fermentation tanks C3 and B3 are connected in series to become two continuous fermentation tanks D1 and D2, the original A3 continuous three-stage tank is changed to an intermittent fermentation tank, and the original three-stage continuous fermentation is changed to a two-stage continuous fermentation, forming 4 two-stage continuous lines including line A, line B, line C and line D. After the transformation, there are 8 continuous fermentation tanks and 7 intermittent fermentation tanks, such as Figure 3 shown.

[0063] The saccharification mash (brown rice raw material) with 30.5% by weight of yeast and dry matter was pumped into A1 at an inoculation ratio of 50%. After A1 was filled with feed for 16 hours, it began to pump feed to A2. A2 was filled with feed for 16 hours. Line B, Line C, and Line D were carried out in the same way. After A2, B2, C2, and D2 were filled with tanks, the materials were mixed into a pipeline and pumped into intermittent fermentation tanks A3, A4, A5, B4, B5, C4, and C5 in sequence for intermittent fermentation. The intermittent fermentation lasted for 38 hours. The materials after intermittent fermentation were pumped into a mature mash tank to obtain a mature mash. Anjuntai was added during the fermentation process, and the addition amount of Anjuntai was about 0.002 volume‰.

[0064] Clean one line every 4 days. First, gradually stop feeding A1 with yeast and mash, then feed A1 to A2. Empty A1 for 16 hours and turn off A1 discharge pump. Immediately perform CIP online cleaning on A1. CIP has 3 nozzles per tank, installed at an angle of 120°. After A1 is cleaned, open A1 feed valve to continue feeding. At the same time, A2 feeds the intermittent fermentation tank for 16 hours until A2 is empty, and turn off A2 discharge pump. Immediately perform CIP online cleaning after A2 is empty. After A2 is cleaned, wait for A1 to be full, and turn on A1 discharge pump to feed A2. The cleaning method of B, C and D lines is the same as that of A line. Each intermittent fermentation tank ferments independently, and performs CIP online cleaning after emptying and then feeding.

[0065] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0066] Comparative Example 1

[0067] This comparative example is used to illustrate the fermentation method of the fermentation system before transformation.

[0068] use Figure 1 The system before the modification shown was used for fermentation.

[0069] The saccharification mash (brown rice raw material) with a distiller's yeast and a dry matter content of 30.5% by weight is pumped into A1 at an inoculation ratio of 50%. After A1 is filled with feed for 12 hours, it starts to pump feed to A2. After A2 is filled with feed for 12 hours, it pumps feed to A3. A3 is filled with feed for 12 hours. Line B and line C are carried out in the same way. After A3, B3, and C3 are filled with feed, the materials are mixed into a pipeline and pumped into intermittent fermentation tanks A4, A5, B4, B5, C4, and C5 in turn for intermittent fermentation, and intermittent fermentation is carried out for 30 hours. The materials after intermittent fermentation are pumped into a mature mash tank to obtain a mature mash. Anjuntai is added during the fermentation process, and the addition amount of Anjuntai is about 0.006 volume‰.

[0070] Clean the continuous line every 3-4 weeks. Clean Line A first, gradually stop feeding A1 with yeast and mash, and then feed A1 to A2. Empty A1 for 10 hours and turn off A1 discharge pump. Immediately perform CIP online cleaning on A1. After A1 is washed, open A1 feed valve to continue feeding. At the same time, A2 feeds A3 for 10 hours to empty A2, and turn off A2 discharge pump. After A2 is emptied, perform CIP online cleaning immediately. After A2 is cleaned, wait for A1 to be full, and open A1 discharge pump to feed A2. A3 is discharged to the intermittent fermentation tank, cleaned, and fed again in the same way. After Line A is cleaned, clean Line B and Line C in the same way as Line A. Each intermittent fermentation tank ferments independently, and performs CIP online cleaning after emptying and then feeds.

[0071] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0072] Comparative Example 2

[0073] This comparative example is used to illustrate the fermentation method of the fermentation system before transformation.

[0074] Ethanol fermentation was carried out in the fermentation system described in Comparative Example 1, except that the dry matter content of the saccharified mash was 27 wt %.

[0075] The alcohol content, residual reducing sugar content and volatile acid content in the mature mash were determined, the acid difference was calculated, and the amount of Anjuntai required for producing one ton of ethanol (based on 99.5% v / v) was calculated. The specific results are shown in Table 1.

[0076] Table 1

[0077]

[0078] It can be seen from the results in Table 1 that the fermentation system improved by the method of the present invention for ethanol fermentation can increase the alcohol content in the mature mash, reduce the residual reducing sugar and volatile acid contents, and can also reduce the amount of antibacterial agent used, indicating that the scheme described in the present invention can significantly improve the fermentation effect without changing the fermentation capacity, and has a significantly better antibacterial effect.

[0079] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An improved method for semi-continuous fermentation ethanol production process, characterized in that: The fermentation system for semi-continuous fermentation comprises a continuous fermentation section and an intermittent fermentation section connected in series, wherein the continuous fermentation section comprises a continuous fermentation production line connected in parallel, and the intermittent fermentation section comprises an intermittent fermentation tank connected in parallel; the method comprises: the fermentation system comprises 4 continuous fermentation production lines connected in parallel and 3 intermittent fermentation tanks connected in parallel, each continuous production line comprises 3 continuous fermentation tanks; or, The fermentation system includes 4 continuous fermentation production lines connected in parallel and 7 intermittent fermentation tanks connected in parallel, and each continuous production line contains 2 continuous fermentation tanks; Wherein, the residence time of the material in each of the continuous fermentation tanks is 12-20 hours; the residence time of the material in each of the intermittent fermentation tanks is 5-40 hours; The method also includes increasing the cleaning frequency of each continuous fermentation production line to 3-10 days / time.

2. The method according to claim 1, wherein: The fermentation time of the fermentation system is 60-72h.

3. The method according to claim 1 or 2, wherein: The method of cleaning the continuous fermentation production line includes: cleaning one continuous fermentation production line at a time; during the cleaning process of each continuous fermentation production line, cleaning is performed sequentially from front to back along the direction of the materials.

4. The method according to claim 1 or 2, wherein: The cleaning method of the intermittent fermentation tank includes: cleaning the intermittent fermentation tank after each intermittent fermentation is completed.

5. The method according to claim 1 or 2, wherein: The cleaning is carried out under the control of a CIP automatic cleaning system.

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