CN113957102A

CN113957102A - Method for continuously producing ethanol

Info

Publication number: CN113957102A
Application number: CN202110970482.3A
Authority: CN
Inventors: 李凡; 应汉杰; 袁敬伟; 李义; 陈勇; 佟毅; 邓衍宏; 卢久灵; 刘庆国; 汪虎; 刘桂文; 柳东
Original assignee: Nanjing Institute Of White Biotech Co ltd; SUZHOU COFCO BIOCHEMICAL CO Ltd; COFCO BIOCHEMICAL ENERGY (ZHAODONG) CO LTD; Nanjing Tech University; Cofco Jilin Bio Chemical Technology Co Ltd
Current assignee: Nanjing Institute Of White Biotech Co ltd; SUZHOU COFCO BIOCHEMICAL CO Ltd; COFCO BIOCHEMICAL ENERGY (ZHAODONG) CO LTD; Nanjing Tech University; Cofco Jilin Bio Chemical Technology Co Ltd
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2022-01-21

Abstract

The invention relates to the field of ethanol production, and discloses a method for continuously producing ethanol, which comprises the following steps: inoculating the yeast cells into a fermentation tank for immobilization to obtain immobilized yeast cells; then carrying out continuous fermentation in the presence of the immobilized cells in the fermentation tank to obtain ethanol; wherein the fermenter contains a carrier device. The invention uses the fermentation tank containing the carrier device to immobilize the yeast cells, and then carries out continuous fermentation, the fermentation intensity is high, and the continuous fermentation batch can be more than 50 times. And the fermentation tank has the advantages of simple structure, easy operation, large loading of the carrier, good mass transfer effect, high adsorption speed and the like.

Description

Method for continuously producing ethanol

Technical Field

The invention relates to the field of ethanol production, and discloses a method for continuously producing ethanol.

Background

At present, fuel ethanol is mainly produced by microbial fermentation, however, in the fermentation process of traditional fuel ethanol enterprises, due to the reasons of poor tolerance of microbial cells, short life cycle, difficulty in repeated use and the like, the problems of low product concentration, low product yield, low production efficiency and the like occur.

In recent years, immobilization technology has gained more and more extensive attention and application in fuel ethanol fermentation production. The immobilized cell has the advantages of short fermentation time, high product conversion rate, stable production and the like when being used for producing ethanol by fermentation. The traditional immobilization technology mainly uses a gel embedding technology, namely cells are immobilized and fermented by carrageenan, calcium alginate, sodium alginate and the like. Although the embedding carrier has the advantages of convenient molding, high immobilization density and the like, the embedding carrier has low mechanical strength, weak mass transfer and poor antimicrobial decomposition capability; meanwhile, due to mass transfer limitation, cell self-renewal is difficult to realize.

Disclosure of Invention

The invention aims to solve the problems of low efficiency of direct fermentation of strains, poor mass transfer effect of immobilized fermentation for ethanol production and the like in the prior art, and provides a method for continuously producing ethanol.

In order to achieve the above object, the present invention provides a method for continuously producing ethanol, comprising:

inoculating the yeast cells into a fermentation tank for immobilization to obtain immobilized yeast cells; then carrying out continuous fermentation in the presence of the immobilized cells in the fermentation tank to obtain ethanol;

wherein the fermentation tank comprises a tank body and a carrier device; the tank body comprises a tank top, a cylinder body and a tank bottom;

wherein the carrier device is filled in the cylinder body;

the carrier device comprises at least two grids parallel to the transverse axis of the fermentation tank, a vertical column connected with the grids, and a fiber carrier arranged on the vertical column.

Preferably, the method further comprises: when the ethanol concentration in the fermentation liquor is more than 10 volume percent, carrying out injection gasification and condensation treatment on the fermentation liquor from the fermentation tank to obtain gas phase condensate and liquid phase condensate; and conveying the liquid phase condensate to the fermentation tank for fermentation.

The yeast cells are immobilized by the fermentation tank containing the carrier device and then continuously fermented, so that the cell activity and the fermentation efficiency can be improved, the fermentation intensity is high, and the continuous fermentation batch can be more than 50 times. Meanwhile, the fermentation tank has the advantages of simple structure, easy operation, large loading of the carrier, good mass transfer effect, high adsorption speed and the like.

In addition, the high-concentration final product has obvious inhibition and toxic effects on the thalli. Generally, when the concentration of the fuel ethanol reaches more than 8%, the obvious inhibition effect on microorganisms is generated. Although the inhibition of high-concentration products on fermentation can be reduced by diluting the feed liquid, the low ethanol concentration can cause the efficiency of downstream separation and extraction to be lower; and meanwhile, the cost is increased due to the consumption of a large amount of water for dilution. In a preferred embodiment of the present invention, ethanol production and separation are coupled, so that when ethanol is produced by fermentation, ethanol-containing fermentation broth and yeast cells can be separated on line, thereby eliminating or greatly reducing the inhibitory effect of high-concentration ethanol on yeast, promoting ethanol formation, increasing ethanol yield (ethanol yield-ethanol quality/fermentation time), and simplifying the subsequent purification steps.

Drawings

FIG. 1 is a schematic view of a fermenter according to the present invention;

FIG. 2 is a schematic cross-sectional view of a carrier device in a fermenter according to the present invention;

FIG. 3 is a schematic view of a stirring device in a fermenter according to the present invention;

FIG. 4 is a schematic view of a blade (including a U-shaped paddle) according to the present invention;

FIG. 5 is a schematic view of a blade (including a W-type blade) according to the present invention;

FIG. 6 is the results of mass transfer simulation using the paddle depicted in FIG. 4 in example 1 of the present invention;

FIG. 7 is the result of mass transfer simulation using the paddle of FIG. 5 in example 1 of the present invention;

FIG. 8 is a schematic flow chart of the system of the present invention.

Description of the reference numerals

T0, fermentation tank; t1, injection device; t2, a condensing unit; t3, vacuum extractor; t4, an ethanol collecting device;

1. a tank body; 2. a carrier device; 3. a stirring device; 4. a feed inlet; 5. a discharge port;

21. a grid; 22. a column; 221. supporting the upright post; 222. a carrier column; 23 a fibrous support; 31. a power unit; 32. a coupling; 33. a stirring shaft; 34. a paddle; 35 of a support member.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a method for continuously producing ethanol, which comprises the following steps:

wherein the carrier device is filled in the cylinder body;

The shape of the fermentation tank is not particularly required as long as the fermentation tank can be used for producing ethanol by yeast fermentation.

The aspect ratio of the fermenter can be selected within wide limits, preferably 1.5 to 4. It should be understood that when the bottom of the fermenter is of the inverted cone structure, the height of the inverted cone structure can be ignored.

The carrier device is filled in the cylinder body, and the bottom of the carrier device can be kept horizontal to the bottom of the cylinder body or slightly higher than the bottom of the cylinder body. It will be appreciated that the support means is not in contact with the stirring means in order not to interfere with the normal operation of the stirring means, i.e.the central region of the fermenter is the non-support zone.

The shape of the grid may not be particularly limited as long as it can be filled in the fermenter and can provide a sufficient number of attachment sites to which a sufficient number of posts can be attached. Preferably, the shape of the grid is circular. That is, the center of the circular grid is the stirring device.

Preferably, the diameter (i.e., inner diameter) of the inner circle of the grating is 20-40% of the diameter of the fermenter, such as 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40%, and any range therebetween. For example, when the diameter of the fermentation tank is 1m, the inner diameter of the grating is 0.2m-0.4 m.

Preferably, the diameter (i.e., outer diameter) of the outer circle of the grating is 90% or more of the diameter of the fermenter, such as 90, 92, 94, 96, 98, 100% and any range between any two values. It should be understood that 100% here means that the outer edge of the grid is in direct contact with the fermenter cylinder, the diameter of which is substantially the same as the diameter of the fermenter.

The carrier device may be fixedly attached or detachably attached to the barrel.

Preferably, the height of the carrier means is 60-80% of the height of the barrel. That is, the top of the carrier device may not reach the upper edge of the barrel.

The sum of the thicknesses of the two uppermost and lowermost grids of the carrier device and the distance between them can be regarded as the height of the carrier device.

Other grids can be additionally arranged in the carrier device, and the number of the grids can be 1-2.

The porosity of the grid can be selected within a wide range as long as it is capable of keeping the material in the fermenter unobstructed, and preferably the porosity of the grid is 65-90%, such as 65, 70, 75, 80, 85, 90% and any range between any two values.

Preferably, the column comprises a support column and a carrier column; wherein, at least two the support post is along grid inner edge evenly distributed.

The support columns are used for connecting the two grids at the top and the bottom. The number thereof may not be particularly limited as long as the grating can be stabilized.

The carrier upright columns are connected between two adjacent grids, and the carrier upright columns on the upper layer and the lower layer can be connected or disconnected.

The number of said carrier columns can be chosen within wide limits and can be selected by the person skilled in the art according to the size of the fermenter.

The diameter of the carrier column and the support column can be selected by those skilled in the art according to the size of the fermenter, and will not be described in detail herein.

The material of the grating and the upright is not particularly limited, and may be, for example, stainless steel.

Preferably, one end of the fiber carrier is fixed on the carrier upright post, and the other end is in a free state.

Preferably, the fibrous support is in the form of a sheet, strip or thread.

Preferably, the fibrous support is in the form of a sheet; wherein the thickness of the fiber carrier is 1.5-3 mm.

The length of the fibrous support can be chosen within wide limits, as long as it is less than the distance between the support pillars.

The material of the fiber carrier is not particularly limited as long as the yeast can be immobilized, and may be, for example, at least one of plant fibers (e.g., cotton, hemp, bamboo fibers, etc.), animal fibers, and artificial fibers (e.g., acrylic fibers, polyester fibers, etc.). For example, a towel or the like can be used as the fibrous support.

Preferably, the loading of the fibrous support is 12-20g/L volume of fermentation broth (e.g., can be 12, 13, 14, 15, 16, 17, 18, 19, 20g/L volume of fermentation broth and any range of compositions between any two values), i.e., the loading is calculated based on the volume of fermentation broth.

The fermentation tank can be externally connected with a condensing device and used for controlling the temperature of fermentation liquor in the fermentation tank.

In the present invention, the fermentation tank may further include other structures such as a feeding device and a discharging device, etc. The feeding means may be located at the top of the tank and the discharging means may be located at the bottom of the tank.

The feed device may include a feed tube and a feed inlet.

Preferably, the number of the feed inlets is 1-4.

Preferably, the feed inlet is in the form of a nozzle. The number of nozzles is selected within wide limits, preferably from 3 to 12.

The discharging device can comprise a discharging pipe and discharging ports, and the number of the discharging pipe and the number of the discharging ports can be at least one respectively.

Preferably, the fermenter further comprises a stirring device.

Preferably, the stirring device is positioned on a central shaft inside the tank body and used for stirring the materials in the fermentation tank.

Preferably, the stirring device comprises a power unit, a coupler, a stirring shaft, at least one blade and a support piece connected with the bottom of the tank from top to bottom, and the stirring device is connected with the top of the tank through the coupler.

The power unit may be an electric motor or other device capable of providing energy.

Preferably, the blade is selected from at least one of a diagonal blade, a W-shaped blade and a U-shaped blade.

Preferably, the number of the paddles is 3-6.

The size of the blades can be selected within a wide range, and a person skilled in the art can select suitable blades according to the size of the fermenter.

In a preferred embodiment of the present invention, the blade includes a diagonal blade and a W-shaped blade. At least 2 inclined blades (such as 3) are positioned above the W-shaped blades.

Preferably, the fermenter is further provided with a circulation device for circulating the fermentation broth in the fermenter.

The circulation device can be, for example, a pump, and the circulation device can be connected to the inlet and outlet of the fermentation tank, respectively, so that the fermentation liquid circulates from the inlet to the fermentation tank through the circulation device. The circulating device can also be connected with a heat exchange device for controlling the temperature.

In the present invention, the mode of liquid circulation provided by the above-mentioned device, that is, liquid circulation, means that the fermentation liquid in the fermentation tank is circulated by the circulation device.

In the present invention, the feedstock for ethanol production may be a cellulosic feedstock or a starchy feedstock, preferably a starchy feedstock such as wheat, rice, corn, tapioca, sorghum, and the like.

It is understood that the terms "wheat", "maize", "rice", "cassava" and "sorghum" do not refer to the whole plant itself, but to the parts or organs thereof having a high starch content, i.e. the wheat seeds, maize seeds, rice seeds, cassava tubers, sorghum seeds, with or without husk.

In the present invention, unless otherwise specified, wheat is wheat grains, rice is brown rice, and corn is corn grains.

The feedstock may be treated by methods conventional in the art to provide a fermentation medium, seed medium, propagation medium, or the like, such as by crushing, slurrying, liquefaction, and optional saccharification (which may be performed simultaneously with or separately from the fermentation process).

The pulverization method is not particularly limited, and various pulverization methods commonly used in the art may be used, and in order to improve the effect of the subsequent treatment, it is preferable that the pulverization conditions are such that 80% by weight or more of the pulverized product can pass through a 20-mesh sieve, more preferably at least 85%, and still more preferably at least 95% of the pulverized product can pass through a 20-mesh sieve.

In the invention, the water for size mixing is used for size mixing, and the water for size mixing can be process water or materials obtained in a production process (such as evaporation condensate obtained in a subsequent evaporation process).

Preferably, the solids content of the material (generally referred to as starch slurry) in the size mixing process is 20-40 wt%, preferably 22-33 wt%, and may be, for example, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 wt% or any value within the range of any two points, more preferably 25-32 wt%.

The temperature of the slurry mixing can be selected by those skilled in the art according to the kind of the raw material.

Wherein, the size mixing process can also comprise a step of adjusting the pH, and the adjusted pH is preferably 3-8, more preferably 4-7.

In the present invention, the purpose of the liquefaction is to convert the starch slurry into fermentable sugars. Therefore, any method conventionally used in the art that can achieve the purpose of liquefaction treatment is suitable for the present invention.

Specifically, the process of liquefying may include: and adding amylase into the starch slurry for liquefaction to obtain liquefied liquid.

Preferably, the amount of amylase added is 10-80U/g dry basis starchy material, more preferably 15-60U/g dry basis starchy material.

Preferably, the liquefaction temperature is from 55 to 120 deg.C, more preferably from 65 to 105 deg.C.

Preferably, the liquefaction pH is in the range of 3 to 8, more preferably 4 to 7.

Preferably, the liquefaction time is between 0.2 and 10h, more preferably between 0.5 and 5 h.

Preferably, the saccharification mode comprises: and adding saccharifying enzyme into the liquefied liquid for saccharification to obtain a saccharified liquid. The saccharifying enzyme can be a saccharifying enzyme common in the art.

The amount of the saccharifying enzyme can be selected within a wide range, and preferably the amount of saccharifying enzyme is 100-300U per 1g of dry starchy material.

In the present invention, the yeast cell may be a yeast cell conventionally used in the art for producing ethanol, and may be, for example, a high temperature-resistant yeast available from Angel yeast.

Preferably, the yeast cells used for immobilization are seeded in the form of seed liquid.

The preparation method of the seed solution can be to inoculate the yeast cells in a seed culture medium for propagation culture to obtain the seed solution.

Preferably, the condition of the propagation includes: the temperature is 25-35 ℃ and the time is 18-24 h.

Preferably, the seed culture medium comprises at least one of corn saccharification liquid, molasses, cassava saccharification liquid, wheat saccharification liquid and rice saccharification liquid, and urea (preferably 0.1-0.5 g/L).

Preferably, the total sugar concentration of the seed culture medium is 30-220g/L, and the pH is 4-6.

The expanding culture can be carried out in a seeding tank, and the rotating speed in the expanding culture process is adjusted according to the size of the seeding tank.

Preferably, the number of yeast cells in the seed liquid is 2.5X 10⁸cfu/mL or more.

Preferably, the seed solution is inoculated in an amount of 5 to 15 vol%.

Preferably, the immobilization method comprises: the yeast cells are adsorbed on the fiber carrier by means of liquid circulation for culture.

Preferably, the liquid circulation has a flow rate of 0.2-2BV (e.g., may be any value within the range of 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2BV and any combination of the two). Wherein, 1BV means that the circulation volume of 1 hour is the actual liquid filling volume of the fermentation tank. For example, when the actual liquid loading of the fermentation tank is 1000L, 1BV means that 1000L of fermentation broth was circulated for 1 hour.

Preferably, the temperature of the culture is 25-28 ℃, and the culture time is 36-48 h.

During the culture process, a nutrient can also be fed, and the nutrient can be saccharification liquid and/or urea.

After completion of the culture, the culture medium in the fermentor was discharged to obtain immobilized yeast cells (supported on a fibrous carrier). The culture medium may be discharged entirely or partially, and the discharge amount of the culture medium is preferably 80 to 95 vol% of the volume of the culture medium, and may be any value within the range of, for example, 80, 85, 90, 95, 98 vol% or any two points.

In the presence of the immobilized yeast cells, continuous fermentation can be carried out, and batch fermentation can be combined in the continuous fermentation process, for example, one fermentation can be carried out in each batch fermentation process, and fed-batch fermentation can also be carried out by feeding nutrients. The fermentation of each batch is continuously carried out, namely the continuous fermentation is realized.

During the continuous fermentation process, partial fermentation liquor (accounting for less than 20 volume percent of the total volume of the fermentation liquor) can be reserved for subsequent fermentation, or the fermentation can be carried out after the fermentation liquor is directly discharged completely. Preferably, the method further comprises: after each fermentation, more than 80% by volume of the fermentation broth was discharged from the fermenter.

The fermentation medium in the fermentation process preferably comprises at least one of corn saccharification liquid, molasses, cassava saccharification liquid, wheat saccharification liquid and rice saccharification liquid.

Preferably, the total sugar concentration of the seed culture medium is 220-280g/L, and the pH is 4-6.

Preferably, the temperature of the fermentation is 30-40 ℃.

The fermentation time can be selected according to the fermentation condition, and is preferably 20-50 h.

The rotating speed in the fermentation process is adjusted according to the size of the fermentation tank.

The fermentation is preferably accompanied by a liquid circulation. Preferably, the circulation flow rate of the fermentation broth is between 0.2 and 1.5BV, (e.g., can be any value within the range of 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.5BV and any combination of two).

During the fermentation process, the flow rate of the fermentation liquid can be changed according to the rule of slow first, fast second and slow second. For example, when the total fermentation time is about 42h, the flow rate of the fermentation liquid is 0.2-1BV in the lag phase and logarithmic phase (within about 12 h); in logarithmic phase and stationary phase (about 12-36h), the flow rate of fermentation liquid is 0.2-1 BV; in the late period of stabilization (after about 36h), the flow rate of the fermentation broth is 0.5-1.2 BV. Under this condition, the energy consumption for production in the fermentation and separation coupling process described below can be reduced as much as possible.

In order to overcome the inhibition and toxicity of high-concentration ethanol on yeast cells, the production and separation of ethanol can be coupled, i.e. ethanol is separated while producing.

The system for coupling the production and separation of ethanol preferably comprises, along the material flow, a fermenter, as described above, an injection device and a condensation device; the injection device is used for injecting and gasifying fermentation liquor from the fermentation tank to obtain a gas-phase material and a liquid-phase material; the condensing device is respectively connected with the spraying device and the ethanol collecting device through pipelines and is used for condensing the gas-phase material and conveying the obtained gas-phase condensate to the ethanol collecting device; the condensing device is also connected with the spraying device and the fermentation tank through pipelines respectively and is used for condensing the liquid-phase material and conveying the obtained liquid-phase condensate to the fermentation tank.

Preferably, the feed inlet of the fermentation tank is sequentially connected with the condensing device and the discharge outlet of the fermentation tank, and is used for cooling the fermentation liquor in the fermentation tank.

The condensing unit may comprise at least one condensing device for cooling the material.

It should be understood that the system also comprises at least one switch and at least one pump for conveying the materials, and those skilled in the art can set the switch and the pump at appropriate positions as required, and achieve the purpose of conveying and processing the materials by regulating the switch and the pump.

Preferably, the system further comprises a vacuum-pumping device, wherein the vacuum-pumping device is respectively connected with the spraying device and the condensing device through pipelines and is used for conveying the gas-phase material into the condensing device. The evacuation device may be, for example, a vacuum pump. The vacuum degree of the vacuum pump is preferably-30 kPa to-100 kPa.

Preferably, the temperature of the condensation is 16-20 ℃.

The ethanol collection device may be, for example, a collection tank.

It should be understood that the system may also include a seed tank for providing seeds for fermentation in the fermentor.

The system may also include other means for producing ethanol by fermentation, such as equipment or devices for preparing the fermentation medium, etc.

The present invention will be described in detail below by way of examples.

The experimental procedures in the following examples are conventional unless otherwise specified.

Wherein, the calculation formula is as follows: the ethanol mass is the sum of the mass of ethanol in the fermentation tank and the mass of ethanol in the ethanol collection device (collection tank), and the mass is concentration volume.

The enzymatic activity of the liquefying enzyme is defined as: 1mL of enzyme solution is liquefied into 1 gram of soluble starch in 1 hour under the conditions of 85 ℃ and pH5.5. In the following examples, the enzymatic activity of the liquefying enzyme used was 7 ten thousand U/mL.

The enzymatic activity of the saccharifying enzyme is defined as: 1mL of saccharifying enzyme decomposes soluble starch for 1 hour to generate gram of glucose under the conditions of 40 ℃ and pH value of 4.5, namely 1 enzyme activity unit. In the following examples, the activity of the saccharifying enzyme used was 3 ten thousand U/mL.

The raw materials and reagent materials used in the following examples are all commercially available products unless otherwise specified.

The point values referred to in the following examples may, in practical cases, be shifted up or down by 5%.

Example 1: mass transfer simulation of 1200 ton fermentor.

The fermentation tank shown in figure 1 comprises a tank body 1, a carrier device 2, a stirring device 3, a feeding device 4 and a discharging device 5; the tank body T1 comprises an arc-shaped tank top, a cylinder body and an inverted cone-shaped tank bottom; wherein the carrier device 2 is filled in the cylinder. Be provided with 2 feed arrangement 4 on the convex tank deck, contain 2 inlet pipes and 2 feed inlets, the back taper tank bottoms is provided with 1 discharging pipe and 1 discharge gate.

As shown in FIGS. 1 and 2, the carrier device 2 comprises three grids 21 parallel to the transverse axis of the fermenter, uprights 22 connecting the grids, and fiber carriers 23 arranged on the uprights. The upright 22 comprises a support upright 221 and a carrier upright 222; wherein, 8 support columns 221 are uniformly distributed along the inner edge of the grid 21. Two ends of 400 carrier columns 222 are respectively connected with 2 adjacent grids, and the upper and lower carrier columns can be connected or disconnected and are uniformly distributed. One end of the fiber carrier 23 is fixed to the column 42 and the other end is in a free state.

As shown in fig. 3, the stirring device 3 is provided with a power unit 31 (motor), a coupler 32, a stirring shaft 33, a blade 34 and a support member 35 connected with the bottom of the tank in sequence from top to bottom, and the stirring device 3 is connected with the top of the tank through the coupler 32; wherein, the paddle 34 comprises an inclined paddle (3) and a W-shaped paddle or a U-shaped paddle, and the inclined paddle is arranged above the W-shaped paddle or the U-shaped paddle.

Specific ANSYS Fluent simulation parameters: the diameter of the fermentation tank is 9.7m, the height of the tank top is 1.25 m, the height of the cylinder body is 16.5 m, and the height of the tank bottom is 2.8 m. The outlet of the feed inlet is provided with nozzles, and the number of the nozzles is 4. The distance between the upper edge of the cylinder and the uppermost grid is 3.0 meters, the height of the carrier device is 13.0 meters, the middle grid is positioned in the middle of the carrier device, the inner diameter of the grid is 2.6 meters, the outer diameter of the grid is slightly smaller than the diameter of the fermentation tank, and the porosity of the grid is 85 percent. The fibrous support 23 is a sheet-like cotton fibrous support having a thickness of 2.5mm, a length of about 6.5 meters and a width of about 0.4 m. The loading of the fiber support 23 was 15g/L fermenter volume. The viscosity of the fermentation liquid is 500mpa · s, and the density of the fermentation liquid is 1.05 g/L.

The stirring speed was controlled to 24rpm using a paddle as shown in FIG. 4 or a paddle as shown in FIG. 5. In fig. 4, the size of the inclined blade is as follows: the diameter is 2.0m, the width of the big end is 0.4m, the width of the small end is 0.2m, the angle is 45 degrees, the number of the blades is 4, and the distance between the blades and the support upright column 221 is 0.3 m; the size of the W-shaped blade is 2.5m in diameter and 0.25m in width.

As a result of the simulation using the paddle shown in FIG. 4, as shown in FIG. 6, the stirring apparatus was rotated at 24rpm, the average liquid velocity in the region without carrier (the inner region formed by the support column 221) was 0.3m/s, the average liquid velocity in the region with carrier was 0.05m/s, and the motor power was 17.59 KW. The right graph shows the velocity profile.

The results of the simulation using the paddle shown in FIG. 5 are shown in FIG. 7, where the stirring apparatus was set to rotate at 24rpm, the average liquid velocity in the region without carrier was 0.33m/s, the average liquid velocity in the region without carrier was 0.052m/s, the velocity distribution was relatively uniform, and the motor power was 8.22 KW. The right graph shows the velocity profile.

The comparison shows that the W-shaped paddle has small amplitude increase of mass transfer effect and obvious reduction of energy consumption, and the W-shaped paddle is more economical, so that the paddle shown in figure 5 is adopted in design, the light-colored representative linear velocity is high, and the visual inspection effect on the whole right side is good.

Example 2: immobilized reactor comparison

Other packing style immobilization reactors were designed with reference to CN210215327U and US10144925B 2.

The immobilization device in CN210215327U is a device in which a fiber adsorbent is placed in a spherical frame and cells are immobilized by suspension. The fiber loading is only 2-4g/L due to the sphere volume. In addition, the spherical frame is made of plastic, so that the damage risk is high in the transportation and filling processes, and the spherical frame has the degradation possibility even if fermented in an acidic environment for a long time. Meanwhile, the manufacturing cost of the spherical carrier is high. Therefore, compared with the device, the fermentation tank of the invention does not have other supports to occupy space, such as plastic balls, steel wire meshes and the like, the carrier amount can reach more than 12g/L, the higher thallus adsorption effect is ensured, simultaneously, the cost is lower, the fiber carrier is more stable, and the service life is longer.

The immobilization mode adopted by US10144925B2 is roll type, i.e. the roll type is made of steel wire mesh, and the fiber material is attached to the surface of the steel wire mesh.

The three modes are respectively subjected to hydromechanical simulation and fermentation effect verification tests in a 10-ton reactor. Wherein the fermentation medium is cassava saccharification liquid, and the total sugar is 230 g/L. The results are shown in Table 1.

TABLE 1

Note:¹the improvement cost is as follows: including labor, material costs, equipment, etc. Wherein the amount of fiber in patent 1 is 3g/L and the latter two are 12 g/L.²Mass transfer effects were calculated as mean linear velocity.³Fermentation period was calculated as 5 batches average.

The lower transformation cost and operation energy consumption, and the higher carrier quantity and mass transfer effect represent that the fermentation efficiency of the fermentation tank of the invention has absolute advantages.

Example 3: adsorption effect of yeast

Preparing a corn liquefied liquid: the material mixing tank is prepared according to the mass ratio of 1:2.5 of material (corn flour) to water, the pH value is adjusted to 5.5, the mixture is pumped to a liquefaction tank, the temperature is increased to 65 ℃, 15U/g (corn flour dry weight) of liquefying enzyme is added, the mixture is maintained for 30min, the temperature is continuously increased to 96 ℃, and the mixture is maintained for 40-60min, so that the liquefaction is thorough. Cooling to 60 deg.C, adjusting pH to about 4.0, and pumping into seed tank.

Seed culture: adding 180U/g saccharifying enzyme into a pipeline connected with the seed tank to saccharify the corn liquefied liquid to obtain corn saccharified liquid, wherein the total sugar concentration is 220 g/L. High-temperature resistant Angel yeast powder (1 mg of yeast powder is added to each liter of corn saccharification liquid) and 0.2g/L of urea are put into a seeding tank, and the mixture is cultured for 20 to 24 hours at 28 ℃ in a ventilation mode (0.3vvm) until the yeast number reaches 2.5 hundred million/mL, namely the seeding liquid.

And (3) an immobilization process: the seeds were pumped into a fermentor as in example 1 (the stirring apparatus was a stirring apparatus with W-shaped blades as shown in FIG. 5) and immobilized. The circulation amount is 1BV, the rotating speed is 15r/min, the temperature is 27 ℃, the culture is about 42 hours, and in the period, saccharified liquid with 20 percent of the total volume of the fermentation liquid is added. At the end of the culture, the amount of the carrier-adsorbed bacteria reached 3.0 hundred million/mL (the amount of adsorption was characterized by the extent of decrease in the concentration of free bacteria in the fermentation broth).

Fermentation: discharging partial liquid after immobilization, reserving 10 volume percent of the liquid in a fermentation tank as fermented seed liquid, and adding new corn saccharification liquid for fermentation. The rotation speed of 20r/min, the temperature of 33 ℃ and the circulation volume of 0.5BV, the culture is carried out for 24 hours, the average yeast concentration in the fermentation liquid in the fermentation process is 1.1 hundred million/mL, the residual total sugar is 0.85g/100mL, and the alcohol content is 12.8% (v/v). Run 2 repeated run 1 with an average yeast concentration of 0.88 million/mL, residual total sugar of 0.92g/100mL, and alcohol content of 13.1% (v/v). After batch 2 was completed, the fermented mash was completely emptied and supplemented with new fermentation medium for batch 3, and then batches 4 and 5 were fermented according to the same method. Data from fermentation runs 1-5 are shown in Table 2 below:

TABLE 2

The method of the invention has the advantages of fast thallus adsorption rate and large adsorption quantity in the immobilization process. From the data analysis of Table 2, the fermentation batch is stable, the number of free yeast is low (the concentration of the traditional free yeast fermentation thallus is 2.5-3.0 hundred million/mL), and the fermentation effect mainly depends on immobilized yeast; and the yeast mortality is small (the mortality of the traditional free fermentation final yeast is more than 75%, the deformation is serious), which indicates that the yeast amount and the yeast activity on the carrier are stable.

In addition, compared with the traditional free fermentation (namely the current domestic ethanol fermentation process) period (44-48 hours), the fermentation period of the immobilized yeast is only about 24 hours, and the ethanol fermentation yield is obviously improved. The comprehensive results show that the immobilized yeast has good adsorption effect and obvious fermentation advantages.

Example 4: high concentration fermentation experiment of rice

Rice liquefaction: mixing the materials according to the mass ratio of 1:1.6, wherein half of the materials are hulled rice powder, the other half of the materials are non-hulled rice powder, and adjusting the pH value to about 5.5. Preheating by an ejector and pumping into a liquefaction tank, adding 15U of liquefying enzyme into 1g of raw material, and liquefying at 90 ℃ for 2 hours to obtain the rice liquefied liquid. Then the temperature is reduced to 30 ℃ by a heat exchanger, and 180U of saccharifying enzyme is added according to 1g of raw material in a pipeline of a material pump to a fermentation tank (all fermented mature mash is discharged after 5 th batch in example 3, and the rice liquefied liquid is saccharified and then sent to the fermentation tank for 6 th batch fermentation). The circulation quantity is 0.8BV, the rotating speed is 24r/min, the temperature is 33 ℃ and the reduction of the residual total sugar is not obvious, and the death rate of the yeast in the fermented mash exceeds 90 percent.

The fermentation is carried out for 20 batches, the average fermentation period is about 44 hours, the average residual total sugar is 1.80g/100mL, the average alcohol content is 15.6% (v/v), the average ethanol concentration is 123.8g/L, the total mass of ethanol is 100.28 tons, the average yeast concentration in the fermentation process is 0.85 hundred million/mL, and the final yeast death rate is 34%.

The same material, the fermentation period of the traditional free process is about 68 hours, the residual sugar is about 2.1g/100mL, the fermentation alcohol content is about 15.1% (v/v), the ethanol concentration is about 120.1g/L, the yeast concentration is about 2.8 hundred million/mL, and the final yeast death rate is over 95%. In comparison, under the condition of high-concentration fermentation, the immobilized yeast has higher ethanol tolerance and higher fermentation yield and output.

Example 5: fermentation separation coupling

The system shown in fig. 8 is used for fermentation separation coupling, and the fermentation separation coupling is switched at the later stage of fermentation under the condition of relatively high ethanol concentration, so that the ethanol yield is improved.

The system shown in FIG. 8 comprises a fermentation tank T0, a spraying device T1, a vacuum pumping device T3, a condensing device T2 and an ethanol collecting device T4 which are connected in series, and a plurality of pumps and switches. The injection device T1 is used for carrying out injection gasification on the fermentation liquor from the fermentation tank T0 to obtain a gas phase material and a liquid phase material; the condensing device T2 is respectively connected with the spraying device T1 and the ethanol collecting device T4 through pipelines and is used for condensing the gas-phase material and conveying the obtained gas-phase condensate to the ethanol collecting device T4; the condensing device is also connected with the spraying device T1 and the fermentation tank T0 through pipelines respectively, and is used for condensing the liquid phase material and conveying the obtained liquid phase condensate to the fermentation tank T0. The feed inlet of the fermentation tank T0 is sequentially connected with a condensing device and the discharge outlet of the fermentation tank T0 and is used for cooling the fermentation liquor in the fermentation tank T0.

5.1 the fermentation is influenced by starting the separation coupling mode under different ethanol concentrations.

The same procedure as in example 4 was repeated except that the rice mash was used as a starting material and the fermentation temperature was 34 ℃ at batches 26 to 28. When the alcohol content reaches 10% (v/v), pumping the fermentation liquor in the fermentation tank into an injection device T1, and injecting to obtain a gas-phase material and a liquid-phase material, wherein the gas-phase material is pumped into a cooling device T2 for condensation through a vacuum pumping device T3 (vacuum pump), and the obtained condensate is conveyed into an ethanol collecting device T4; the liquid phase material was condensed and pumped back to the fermentor T0. Wherein the vacuum degree of the vacuum extractor T3 is-55 kPa.

Average effect of batches 26-28: the fermentation period was shortened from 44 hours on average in example 4 to about 36 hours. 1.24g/100mL of residual total sugar, 14.1 percent of final alcohol content and 118.6g/L of ethanol concentration; the alcohol content in the alcohol collection tank is 52.0 percent, the alcohol concentration is 430g/L, and the volume is about 25 cubic meters. The total mass of ethanol is 102.75 tons.

In the 29 th to 33 th batches, the fermentation separation coupling treatment was carried out according to the treatment method described above when the alcohol content was 11.5% (v/v), and the average effect of the 29 th to 33 th batches was: the average fermentation period is about 42 hours, the residual total sugar is 1.41g/100mL, the final alcohol content is 14.3 percent, and the ethanol concentration is 120.1 g/L; the alcohol content in the alcohol collection tank is 54.0 percent, the alcohol concentration is 441.0g/L, and the volume is about 22.1 cubic meters. The total mass of ethanol is 104.38 tons.

5.2 circulation volume staged control effects: the staged regulation and control does not influence the yield of the ethanol, and can effectively reduce the energy consumption.

In batches 34-36, the circulation flow rate of the fermentation liquid in the early 12 hours of fermentation is 0.4BV, the circulation volume after 12 hours of fermentation is 0.7BV, and the circulation volume in the later period (the alcohol content is 11.5%, v/v) is 0.90 BV.

The other fermentation conditions were the same as those of batches 29 to 33 in 5.1, with the average effect of batches 34 to 36: the fermentation period is about 39 hours, the residual total sugar is 1.32g/100mL, the final alcohol content is 13.8 percent, the ethanol concentration is 119.2g/L, the alcohol content in the ethanol collection tank is 56.0 percent, the ethanol concentration is 459.0g/L, and the volume is about 23.5 cubic meters. The total mass of ethanol is 104.60 tons. The energy consumption is reduced by about 10 percent.

5.3 adjusting the vacuum degree factor: properly increasing the absolute value of the vacuum degree can effectively reduce the fermentation period and improve the productivity.

The coupling and separating mode is started when the alcohol content reaches 11.5% (v/v) in batches 37 to 41, the vacuum degree is-65 KP, and the other operations have the average effect of the batches 37 to 41 in example 5.2: the fermentation period is about 34 hours, the residual total sugar is 1.30g/100mL, the final alcohol content is 13.6 percent, the ethanol concentration is 118.7g/L, the alcohol content in the ethanol collection tank is 57.8 percent, the ethanol concentration is 472.9g/L, and the volume is about 24.2 cubic meters. The total mass of ethanol is 104.74 tons.

And a plurality of batches of fermentation experiments are carried out subsequently until the fermentation state of the 50 th batch is still good, and normal fermentation can be continued, so that the fermentation tank can realize at least 50 batches of fermentation times.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A process for the continuous production of ethanol, comprising:

wherein the carrier device is filled in the cylinder body;

2. The method of claim 1, wherein the carrier device is fixedly or removably attached to the cartridge;

preferably, the height of the carrier means is 60-80% of the height of the barrel.

3. The method of claim 1, wherein the grid is annular;

preferably, the diameter of the inner circle of the grating is 20-40% of the diameter of the fermentation tank;

preferably, the diameter of the excircle of the grating is more than 90% of the diameter of the fermentation tank;

preferably, the porosity of the grid is 65-90%.

4. The method of claim 3, wherein the column comprises a support column and a carrier column; wherein, at least two the support post is along grid inner edge evenly distributed.

5. The method of claim 1, wherein the fibrous support is fixed at one end to a support column and at one end is in a free state;

preferably, the fiber carrier is in a sheet shape, a strip shape or a thread shape;

more preferably, the fibrous support is in the form of a sheet; wherein the thickness of the fiber carrier is 1.5-3 mm;

preferably, the loading of the fibrous support is 12-20g/L fermenter volume.

6. The method of claim 1, wherein the fermentor further comprises a stirring device located on a central axis inside the tank for stirring the material within the fermentor;

the stirring device comprises a power unit, a coupler, a stirring shaft, at least one blade and a supporting piece connected with the bottom of the tank from top to bottom, and is connected with the top of the tank through the coupler;

7. The method of claim 1, wherein the fermentor is further configured with a circulation device for circulating the fermentation broth in the fermentor.

8. The method of claim 1 or 7, wherein the immobilizing comprises: adsorbing yeast cells onto a fiber carrier for culture in a liquid circulation mode;

preferably, the flow rate of the liquid circulation is between 0.2 and 2 BV;

9. The method of claim 1, wherein the conditions of the fermentation comprise: the temperature is 30-40 ℃; the circulating flow rate of the fermentation liquor is 0.2-1.5 BV;

preferably, the method further comprises: after each fermentation, more than 80% by volume of the fermentation broth was discharged from the fermenter.

10. The method of any one of claims 1-9, wherein the method further comprises: when the ethanol concentration in the fermentation liquor is more than 10 volume percent, carrying out injection gasification and condensation treatment on the fermentation liquor from the fermentation tank to obtain gas phase condensate and liquid phase condensate; and conveying the liquid phase condensate to the fermentation tank for fermentation.