Fermentation tank device with efficient heat exchange and high mass transfer efficiency

Abstract

The invention relates to a fermentation tank device with efficient heat exchange and high mass transfer efficiency, belongs to the technical field of biological fermentation engineering, and particularly relates to an efficient fermentation tank suitable for production of xanthan gum, polylysine and nisin. The invention provides a fermentation tank device with efficient heat exchange and high mass transfer efficiency, which mainly comprises a tank body and a sealing bottom connected with the bottom of the tank body, and a stirring device is arranged in the tank body. By means of the heat exchanger, the stirring paddle and the gas distributor which are independently designed, the overall performance of the xanthan gum, polylysine and nisin fermentation tank is remarkably improved, and the technical bottlenecks that in a high-viscosity fermentation system, traditional fermentation equipment is difficult in temperature control, low in stirring and mixing efficiency, insufficient in oxygen supply and the like are broken through.

Description

Technical Field

[0001] This invention relates to a fermenter device with high heat exchange and high mass transfer efficiency, belonging to the field of bio-fermentation engineering technology, and in particular to a high-efficiency fermenter suitable for the production of xanthan gum, polylysine and nisin. Background Technology Fermenters are commonly used mechanical devices widely applied in over twenty industries, including food, oil extraction, pharmaceuticals, and cosmetics. They play a crucial role, particularly in the production of products such as xanthan gum, polylysine, and nisin. The industrial production of xanthan gum, polylysine, and nisin typically involves seed culture, fermentation, and separation / purification. Throughout this process, the fermenter, as the core equipment, directly impacts the yield and quality of the products through its temperature control, agitation, and oxygen supply efficiency, thus determining production efficiency and cost. Therefore, fermenter design faces increasingly stringent performance requirements.

[0002] In existing technologies, fermenters for xanthan gum, polylysine, and nisin generally suffer from low heat exchange efficiency. Due to the high viscosity and density of these fermentation broths, the viscosity continuously increases as fermentation progresses, eventually reaching tens to hundreds of thousands of centipoises. This combination of high viscosity and high density significantly reduces the system's internal heat transfer efficiency, resulting in uneven temperature distribution within the fermenter and the formation of temperature gradients. This leads to differences in the metabolic levels of the microorganisms, ultimately affecting the synthesis efficiency and final quality of the product. Traditional jacketed or coiled heat exchange structures struggle to achieve rapid and uniform heat transfer in such high-viscosity systems, often resulting in excessively high or low temperatures in localized areas, severely interfering with normal microbial metabolism and the stable operation of the fermentation process. Therefore, developing a novel fermenter structure capable of achieving efficient heat exchange in high-viscosity, high-density fermentation broths is imperative.

[0003] Besides heat exchange issues, low stirring efficiency is another significant challenge in the fermentation of xanthan gum, polylysine, and nisin. High-viscosity fermentation broths significantly increase stirring resistance, making it difficult for traditional impeller types (such as Rushton impellers, flat-blade impellers, and arrow-blade impellers) to create an ideal flow field within the tank. This results in uneven distribution of nutrients and oxygen, and even dead zones in localized areas, hindering cell growth and product synthesis. Furthermore, traditional impellers often generate significant shear forces in high-viscosity media, easily causing mechanical damage to the cells, reducing their activity, and affecting fermentation efficiency. Simultaneously, maintaining basic stirring efficiency requires significantly increased energy consumption, further driving up production costs. Therefore, designing a low-shear, high-mixing-efficiency impeller structure to meet the operational requirements of high-viscosity systems is crucial for improving fermentation efficiency and reducing costs.

[0004] On the other hand, the fermentation of xanthan gum, polylysine, and nisin are all aerobic processes, placing high demands on a continuous oxygen supply. However, the high viscosity of the fermentation broth significantly reduces the rise and diffusion rates of bubbles, thus decreasing the efficiency of oxygen transfer in the liquid phase. Large bubbles formed by traditional gas distributors in high-viscosity environments are difficult to dissolve, leading to low oxygen utilization and localized hypoxia, thereby inhibiting cell metabolism and product synthesis. Furthermore, high mass transfer resistance further limits the effective transfer of oxygen to the liquid phase.

[0005] Therefore, the existing fermenters suffer from technical bottlenecks such as low temperature control efficiency, poor stirring effect, and uneven oxygen supply in high-viscosity, high-density fermentation systems. There is an urgent need to find a new type of heat exchanger, stirring paddle, and gas distributor to solve these problems. Developing a high-performance gas distributor that can achieve uniform oxygen supply and improve oxygen dissolution efficiency in high-viscosity, high-density systems has become an important direction for improving fermentation results. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a fermenter device with high heat exchange and high mass transfer efficiency, which effectively achieves precise temperature control, uniform mixing, and efficient oxygen supply during fermentation, thereby significantly improving the yield and product quality of xanthan gum, polylysine, and nisin.

[0007] To address the aforementioned problems, this invention provides a fermenter device with high heat exchange efficiency and high mass transfer efficiency, characterized in that it comprises: The tank body has an ellipsoidal sealing bottom attached to its base; The stirring device includes a stirring shaft disposed inside the tank. The stirring shaft is provided with a bottom stirring blade, a middle stirring blade, and an upper stirring blade at three height positions from bottom to top. The stirring shaft can drive the bottom stirring blade, the middle stirring blade, and the upper stirring blade to rotate. The radial flow stirring effect caused by the bottom stirring blade and the axial flow stirring effect caused by the middle stirring blade and the upper stirring blade together form a multi-stage stirring effect. The heat exchangers are evenly distributed along the inner wall of the tank and surround the stirring device, enabling uniform heat exchange of the high-viscosity fermentation liquid inside the tank. The gas distributor is installed throughout the bottom seal.

[0008] Furthermore, the bottom stirring paddle is an FT-6 type stirring paddle, including a disc with a vent hole in the center and six evenly distributed rectangular flat blades connected to the disc; the rectangular flat blades are inclined upward or downward relative to the disc plane and form a uniform inclination angle, and their outer edge contours are tangent or nearly tangent to the outer circumference of the disc body. Furthermore, the intermediate agitator is an A315 type agitator, including a central hub and four swept-back curved blades connected to the central hub. The central hub is provided with an axially penetrating flange connection hole. The four swept-back curved blades are evenly distributed around the circumference of the hub. The torsion angle of the swept-back curved blades changes continuously from the root to the tip, with the root installation angle α = 45° ± 5° and the tip installation angle β = 15° ± 3°.

[0009] Furthermore, the structure of the upper stirring blade is the same as that of the middle stirring blade.

[0010] Furthermore, the six heat exchangers are centrally symmetrically distributed along the inner wall of the tank, and the longitudinal dimension of each heat exchanger is greater than or equal to the height difference between the bottom agitator and the top agitator. The bottom agitator, the middle agitator, and the top agitator are all located within the height range covered by the heat exchanger.

[0011] Furthermore, the heat exchanger is a guqin-shaped heat exchanger, comprising multiple guqin-shaped heat exchange tube groups. Each guqin-shaped heat exchange tube group includes four guqin-shaped heat exchange tubes arranged in parallel at equal intervals. Each guqin-shaped heat exchange tube has symmetrical U-shaped tubes connected to its upper and lower sides and a straight tube structure in the middle.

[0012] Furthermore, the bottom cover has an ellipsoidal structure, and the gas distributor includes a straight pipe section that penetrates the bottom cover and an annular pipe section that connects to the straight pipe section and is located inside the bottom cover. The annular pipe section has multiple gas outlet holes evenly distributed along its circumference.

[0013] Furthermore, the tank body is a cylindrical structure with a height-to-diameter ratio of 1.0-3.0 and an inner diameter-to-outer diameter ratio of 0.9-1.0; the stirring shaft is a cylindrical structure with a diameter-to-tank diameter ratio of 0.02-0.05.

[0014] Furthermore, the ratio of the paddle spacing to the tank height is 0.2-0.5, and the paddle spacing is the distance between the bottom layer agitator and the middle layer agitator or the distance between the middle layer agitator and the top layer agitator.

[0015] Furthermore, the annular section and the straight section of the gas distributor have the same diameter. The annular section is located directly below the bottom stirring paddle. The ratio of the diameter of the annular section to the diameter of the tank is 0.2-0.4. The number of air outlets is 30-60, and the air outlets are circular holes with a diameter of 1mm-5mm.

[0016] The beneficial effects of this invention are: This invention provides a fermenter device with high heat exchange and mass transfer efficiency. Through a self-designed heat exchanger, agitator, and gas distributor, it significantly improves the overall performance of fermenters for xanthan gum, polylysine, and nisin, overcoming the technical bottlenecks of traditional fermentation equipment, such as difficulty in temperature control, low mixing efficiency, and insufficient oxygen supply in high-viscosity fermentation systems. Through optimized design of key components, this invention effectively improves the efficiency and stability of the fermentation process, providing reliable support for the industrial production of high-viscosity bioproducts.

[0017] First, the high-efficiency heat exchanger used in this invention has a structural design that is significantly superior to traditional jacketed or coil-type heat exchange systems. This heat exchanger, by increasing the heat exchange area, optimizing the heat transfer path, and rationally arranging the heat transfer elements, enables rapid and uniform heat transfer in the high-viscosity fermentation broth. This design effectively eliminates temperature gradients within the tank, avoiding localized overheating or overcooling, thereby ensuring the stability and consistency of microbial metabolism and promoting the continuous and efficient synthesis of xanthan gum, polylysine, and nisin.

[0018] Secondly, addressing the issues of high stirring resistance and strong shear force in high-viscosity fermentation broths, this invention introduces a three-layer low-shear stirring impeller. This stirring device significantly reduces mechanical damage to the microbial cells while improving mixing uniformity. The synergistic effect of the multiple impellers effectively eliminates dead zones, ensuring sufficient distribution of oxygen and nutrients within the tank, thereby enhancing mass transfer efficiency. Furthermore, this system also demonstrates excellent energy consumption control, consuming less power than traditional stirring systems, reducing overall fermentation costs, and improving the economy and controllability of the fermentation process.

[0019] Regarding oxygen supply, the high-efficiency gas distributor employed in this invention features a microporous release structure, enabling the continuous release of uniform, fine bubbles into the fermentation broth, significantly increasing the gas-liquid contact area and oxygen dissolution efficiency. Traditional gas distribution methods often suffer from large bubble retention and low oxygen utilization in high-viscosity systems. This invention, through optimized design of bubble size, distribution uniformity, and release rhythm, significantly improves oxygen distribution within the fermenter. This system can precisely match the oxygen requirements of the cells under high-viscosity conditions, enhancing the oxygen mass transfer rate and ensuring normal cell growth and continuous synthesis of the target product.

[0020] In summary, this invention achieves systematic innovation and optimization in three key aspects: heat exchange, stirring, and oxygen supply. This enables the fermenter to exhibit higher stability and efficiency when processing high-viscosity, high-density fermentation broths. Temperature is rapidly and uniformly controlled, stirring and mixing are thorough yet gentle, and oxygen supply is uniform and efficient, effectively solving many problems associated with traditional fermenters. In practical applications, this invention can increase the yield of xanthan gum, polylysine, and nisin by more than 15% within the same fermentation cycle, while reducing energy consumption by more than 10%. It significantly reduces production costs while improving product quality, possessing broad industrial application value. Attached Figure Description

[0021] Figure 1 This is a front view of the overall structure in one embodiment of the present invention.

[0022] Figure 2 This is a perspective view of the overall structure in one embodiment of the present invention.

[0023] Figure 3 This is a perspective view of the overall structure from another angle in one embodiment of the present invention.

[0024] Figure 4 This is a top view of the overall structure in one embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the stirring device in one embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of the bottom stirring paddle structure in one embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram of the upper and middle layer stirring paddle structure in one embodiment of the present invention.

[0028] In the diagram, 1 is the tank body; 2 is the bottom seal; 3 is the stirring shaft; 4 is the bottom stirring paddle; 5 is the middle stirring paddle; 6 is the top stirring paddle; 7 is the heat exchanger; and 8 is the gas distributor. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] In this invention, the terms "first" and "second" are used only to distinguish similar components / parts in different positions or with different characteristics, and have no other limiting meaning; "upper" refers to the direction in which each component is away from the ground, and "lower" refers to the direction in which each component is away from the ground.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The present invention provides a fermenter device with high heat exchange efficiency and high mass transfer efficiency, mainly including a tank body 1 and a bottom seal 2 connected to the bottom of the tank body 1, and a stirring device is provided inside the tank body 1.

[0034] exist Figures 1-4 In the example, tank 1 is a cylindrical structure with a sealed bottom. The sealed bottom is an ellipsoidal structure, meaning the bottom surface of the sealed bottom is an ellipsoidal curved surface. This design eliminates dead corners at the bottom of the tank and allows for perfect flow pattern matching with the stirring paddle, resulting in more uniform temperature, pH, dissolved oxygen, and nutrient concentration of the culture medium inside the tank after stirring.

[0035] In some embodiments, preferably, the height-to-diameter ratio of the tank body 1 is 1.0-3.0, and the ratio of the inner diameter to the outer diameter is 0.9-1.0; the stirring shaft is a cylindrical structure, and the ratio of its diameter to the diameter of the tank body 1 is 0.02-0.05.

[0036] exist Figures 1-3In the example, the gas distributor 8 includes a straight pipe section penetrating the bottom seal 2 and an annular pipe section connected to the straight pipe section and located inside the bottom seal 2. Multiple air outlets are evenly distributed along the circumference of the annular pipe section. These air outlets can be micropores, allowing the gas distributor 8 to form a micropore release structure, enabling the continuous release of uniform, fine bubbles into the fermentation broth, significantly improving the gas-liquid contact area and oxygen dissolution efficiency.

[0037] Furthermore, the bubble size, distribution uniformity, and release rhythm can be optimized by adjusting the size of the vent holes. Preferably, the annular section and the straight section of the gas distributor 8 have the same diameter. The annular section is located directly below the bottom stirring impeller. The ratio of the diameter of the annular section to the diameter of the tank is 0.2-0.4. The number of vent holes is 30-60, and the vent holes are circular with a diameter of 1mm-5mm. This design generates small bubbles, increases the gas-liquid separation area, and prolongs the bubble residence time, thereby improving the dissolved oxygen coefficient. Additionally, the low vent pressure of the small bubbles avoids direct mechanical damage to cells from high-speed airflow.

[0038] exist Figures 1-5 In the example, the stirring device includes a stirring shaft 3 located at the center of the tank. The stirring shaft 3 has a bottom stirring paddle 4, a middle stirring paddle 5, and an upper stirring paddle 6 positioned at three heights from bottom to top. The stirring shaft 3 drives the bottom stirring paddle 4, the middle stirring paddle 5, and the upper stirring paddle 6 to rotate. The radial flow stirring effect caused by the bottom stirring paddle 4 and the axial flow stirring effect caused by the middle and upper stirring paddles together form a multi-stage stirring effect. In fact, the stirring device of this invention is a three-layer low-shear stirring paddle structure. This stirring device significantly reduces mechanical damage to the bacteria while improving mixing uniformity. Furthermore, the synergistic effect of the multiple stirring paddles effectively eliminates dead zones, ensuring sufficient distribution of oxygen and nutrients within the tank, thereby enhancing mass transfer efficiency.

[0039] The heat exchanger 7 has multiple stirring devices evenly distributed circumferentially along the inner wall of the tank and surrounding the center of the tank 1. This allows for uniform heat exchange of the high-viscosity fermentation broth within the tank. The longitudinal dimension of each heat exchanger is greater than or equal to the height difference between the bottom and top stirring blades. The bottom, middle, and top stirring blades are all located within the height range covered by the heat exchanger, thus enabling heat exchange for all three layers. By expanding the heat exchange area, optimizing the heat transfer path, and rationally arranging the heat transfer elements, heat is rapidly and uniformly transferred within the high-viscosity fermentation broth. This design effectively eliminates temperature gradients within the tank, avoiding localized overheating or overcooling, thereby ensuring the stability and consistency of microbial metabolism and promoting the continuous and efficient synthesis of xanthan gum, polylysine, and nisin.

[0040] Preferably, the six heat exchangers are centrally symmetrically distributed along the inner wall of the tank, which ensures uniform heat exchange around the three-layer structure in all 360 degrees and further increases the heat exchange area.

[0041] exist Figures 1-4 In the example, the heat exchanger 7 is a guqin-shaped heat exchanger, comprising multiple guqin-shaped heat exchange tube groups. Each guqin-shaped heat exchange tube group includes four equidistant parallel guqin-shaped heat exchange tubes. Each guqin-shaped heat exchange tube is connected to symmetrical U-shaped tubes on both the upper and lower sides, and has a straight tube structure in the middle. Because the guqin-shaped heat exchanger is an integrated U-shaped structure, the shell side can freely expand or contract, making it very suitable for harsh operating conditions with high temperature and large temperature difference. In addition, the medium flows in pure countercurrent inside the tubes, and the average temperature difference is the largest due to the countercurrent arrangement, resulting in the strongest heat penetration driving force.

[0042] exist Figure 5 , Figure 6 In the example, the bottom stirring paddle 4 is an FT-6 type stirring paddle, which includes a disc with a vent hole in the center and six evenly distributed rectangular flat blades connected to the disc; the rectangular flat blades are inclined upward or downward relative to the disc plane and form a uniform inclination angle, and their outer edge contours are tangent or nearly tangent to the outer circumference of the disc body.

[0043] exist Figure 5 , Figure 7 In the example, the middle layer impeller 5 is an A315 type impeller, including a central hub and four swept-back curved blades connected to the central hub. The central hub has an axially penetrating flange connection hole. The four swept-back curved blades are evenly distributed around the circumference of the hub. The torsion angle of the swept-back curved blades changes continuously from the root to the tip, with a root installation angle α = 45° ± 5° and a tip installation angle β = 15° ± 3°. The upper layer impeller 6 has the same structure as the middle layer impeller.

[0044] Preferably, the ratio of impeller spacing to tank height is 0.2-0.5, and the impeller spacing is the distance between the bottom and middle impellers or the distance between the middle and top impellers. This arrangement ensures an optimal balance between mixing quality, energy efficiency, and mass transfer rate. It avoids densely packed impellers that cause flow field interference, or excessively dispersed impellers that lead to uneven mixing.

[0045] In summary, this invention provides a fermenter device with high heat exchange and mass transfer efficiency, featuring a self-designed heat exchanger, agitator, and gas distributor. By optimizing the core components of the fermenter, it solves problems such as uneven temperature control, poor mixing, and low oxygen supply efficiency caused by the high viscosity and high density fermentation broth in the fermentation of xanthan gum, polylysine, and nisin. The following three specific embodiments describe in detail the application of this fermenter in the fermentation production of xanthan gum, polylysine, and nisin, including the operational details and actual effects of each system.

[0046] Example 1 Xanthomonas aeruginosa was selected. Xanthomonas campestris Xanthan gum fermentation was performed using CCTCC M2015714. First, the inoculum was cultured in seed culture medium for 24 h at 30℃ and 200 rpm until the seed culture OD... 600 The pH value reached approximately 1.2. Before fermentation, the fermenter underwent CIP (clean-in-place) and SIP (sterilize-in-place) processes. The cleaning steps involved sequentially using pure water, hot alkali, acid, and sterile water. The sterilization conditions were 121℃ for 30 min. Sterilized fermentation medium was added to the fermenter, with a formulation of 40 g / L glycerol, 3 g / L peptone, 2 g / L yeast extract, 2.5 g / L sodium nitrate, 2 g / L potassium hydrogen phosphate, 1 g / L potassium dihydrogen phosphate, and 2.5 g / L magnesium sulfate, and the pH was adjusted to 7.0. A 10% seed culture was inoculated to begin the fermentation process.

[0047] During fermentation, temperature is controlled via heat exchanger 7. As the viscosity of the xanthan gum fermentation broth gradually increases, traditional heat exchangers struggle to maintain temperature uniformity. The heat exchanger of this invention employs a multi-tube combined structure, increasing the heat exchange area. Combined with a dynamic heat exchange system, this allows heat to be rapidly and evenly transferred to the fermentation broth. Initially, the temperature is set to 30°C. The PID control system automatically adjusts the cooling water and heating system based on real-time feedback from the temperature sensor, keeping temperature fluctuations within ±0.5°C, ensuring that the cells metabolize and synthesize xanthan gum at the optimal temperature.

[0048] The three-layer agitator system utilizes low-shear impellers, providing efficient radial and axial flow. Initially, the agitation speed is set at 350 rpm. As the viscosity of the fermentation broth increases, the automatic control system gradually increases the speed to 500 rpm to maintain uniform mixing. The impeller surfaces are treated with an anti-stick coating, reducing broth adhesion to the blades, lowering agitation resistance, and effectively preventing cell damage due to excessive shear force. This optimized agitation system ensures uniform nutrient and oxygen distribution within the fermenter, significantly improving cell growth rate and xanthan gum synthesis efficiency.

[0049] The gas distributor employs a microporous gas distributor, enabling uniform oxygen distribution within the fermenter. The oxygen supply system automatically adjusts the air intake based on real-time data feedback from the dissolved oxygen sensor, maintaining a dissolved oxygen concentration above 30%. The rotation of the agitator further promotes bubble dispersion, allowing oxygen to dissolve in the fermentation broth more quickly. During fermentation, the oxygen supply gradually increases from an initial 0.5 vvm to 1.2 vvm, ensuring sufficient oxygen for the cells throughout the fermentation cycle. After 72 hours of fermentation, xanthan gum yield reached 6.2 g / L, an 18% increase compared to traditional fermenters, while energy consumption was reduced by 12% throughout the entire fermentation process.

[0050] Example 2 Use Lactococcus lactis Lactococcus lactis , L. lactis Low-energy nisin fermentation was performed. First, the strain was cultured in seed culture medium for 20 h at 28℃ and 180 rpm. 600 The pH reached 1.0. After CIP and SIP in the fermenter, sterile fermentation medium was added, with a formulation of 35 g / L glucose, 2 g / L yeast extract, 1.5 g / L peptone, 2 g / L ammonium nitrate, 2 g / L potassium dihydrogen phosphate, and 1.5 g / L magnesium sulfate, and the pH was adjusted to 7.2. Fermentation began after inoculating with 8% seed culture.

[0051] During this process, the temperature was set at 28℃ and maintained stable through heat exchanger 7. A dynamic heat exchange system automatically adjusted heating and cooling to achieve precise temperature control, with fluctuations within ±0.3℃. All three layers of impellers in the stirring system used low-shear impellers, with an initial speed of 300 rpm, gradually increasing to 450 rpm as the viscosity of the fermentation broth increased. The low-shear impellers effectively reduced energy consumption while ensuring uniform mixing of the fermentation broth. The oxygen supply system used a microporous gas distributor 8 with a bubble diameter of 0.3 mm and an aeration rate maintained at 0.8 vvm. The fermentation cycle was 60 hours, achieving a nisin yield of 5.8 g / L, with energy consumption reduced by 15% compared to traditional fermenters.

[0052] Example 3 Using Streptomyces alba Streptomyces albulus Polylysine fermentation was performed. The seed culture conditions were: glucose 50 g, (NH4)2SO4 10 g, K2HPO4 0.8 g / L, KH2PO4 1.36 g / L, MgSO4·7H2O 0.5 g / L, ZnSO4·7H2O 0.04 g / L, FeSO4·7H2O 0.03 g, yeast extract 5 g / L, pH 6.8. After inoculating with 10% seed culture, fermentation was carried out in a fermenter.

[0053] During fermentation, the temperature was controlled at 32℃ and maintained stable via heat exchanger 7. The dynamic heat exchange system automatically adjusted the cooling water and heating power based on temperature sensor feedback, ensuring temperature fluctuations did not exceed ±0.5℃. Due to the high viscosity of the fermentation broth, all three layers of impellers in the stirring system used low-shear impellers with an initial speed of 400 rpm, gradually increasing to 550 rpm as density increased. The axial flow and anti-sticking design of the impellers ensured uniform mixing of the fermentation broth while preventing mechanical damage to the cells. The oxygen supply system used a microporous gas distributor with an aeration rate set at 1.0 vvm and a bubble diameter of 2 mm. The dissolved oxygen level was maintained above 35% by the automatic control system to ensure normal metabolism of the cells in the high-viscosity environment.

[0054] After 80 hours of fermentation, the polylysine yield reached 7.0 g / L. Throughout the fermentation process, the stirring and oxygen supply systems operated stably, the cell growth was vigorous, and the temperature, pH, and dissolved oxygen of the fermentation broth were precisely controlled without contamination or abnormal fluctuations. Compared to traditional fermenters, the fermenter of this invention exhibits superior temperature control, mixing, and oxygen supply performance under high viscosity conditions, increasing the polylysine yield by 20% and reducing energy consumption by 10%.

[0055] In summary, the fermenter device of this invention, featuring high-efficiency heat exchange and high mass transfer efficiency, can fully utilize sucrose fermentation products. These three implementation examples demonstrate its application in the efficient fermentation production of xanthan gum, polylysine, and nisin. Through the synergistic effect of the high-efficiency heat exchanger, stirring system, and gas distributor, this invention effectively solves the technical challenges in temperature control, mixing effect, and oxygen supply efficiency of the fermentation broth, significantly improving the yield and quality of xanthan gum, polylysine, and nisin, while reducing production energy consumption and costs. This provides reliable technical support for the industrial fermentation production of xanthan gum, polylysine, nisin, and other materials.

[0056] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A fermenter device with high heat exchange efficiency and high mass transfer efficiency, characterized in that, include: The tank body has an ellipsoidal sealing bottom attached to its base; The stirring device includes a stirring shaft disposed inside the tank. The stirring shaft is provided with a bottom stirring blade, a middle stirring blade, and an upper stirring blade at three height positions from bottom to top. The stirring shaft can drive the bottom stirring blade, the middle stirring blade, and the upper stirring blade to rotate. The radial flow stirring effect caused by the bottom stirring blade and the axial flow stirring effect caused by the middle stirring blade and the upper stirring blade together form a multi-stage stirring effect. The heat exchangers are evenly distributed along the inner wall of the tank and surround the stirring device, enabling uniform heat exchange of the high-viscosity fermentation liquid inside the tank. The gas distributor is installed throughout the bottom seal.

2. The fermentation tank apparatus according to claim 1, characterized in that, The bottom stirring impeller is an FT-6 type stirring impeller, which includes a disc with a vent hole in the center and six evenly distributed rectangular flat blades connected to the disc; the rectangular flat blades are inclined upward or downward relative to the disc plane and form a uniform inclination angle, and their outer edge contours are tangent or nearly tangent to the outer circumference of the disc body.

3. The fermentation tank apparatus according to claim 2, characterized in that, The intermediate agitator is an A315 type agitator, including a central hub and four swept-back curved blades connected to the central hub. The central hub is provided with an axially penetrating flange connection hole. The four swept-back curved blades are evenly distributed around the circumference of the hub. The torsion angle of the swept-back curved blades changes continuously from the root to the tip, with the root installation angle α = 45° ± 5° and the tip installation angle β = 15° ± 3°.

4. The fermentation tank apparatus according to claim 3, characterized in that, The structure of the upper stirring blade is the same as that of the middle stirring blade.

5. The fermentation tank apparatus according to claim 4, characterized in that, The heat exchanger is a guqin-shaped heat exchanger, comprising multiple guqin-shaped heat exchange tube groups. Each guqin-shaped heat exchange tube group includes four guqin-shaped heat exchange tubes arranged in parallel at equal intervals. Each guqin-shaped heat exchange tube is connected to symmetrical U-shaped tubes on both the upper and lower sides and has a straight tube structure in the middle.

6. The fermentation tank apparatus according to claim 5, characterized in that, The six heat exchangers are centrally symmetrically distributed along the inner wall of the tank. The longitudinal dimension of each heat exchanger is greater than or equal to the height difference between the bottom and top agitators. The bottom, middle, and top agitators are all located within the height range covered by the heat exchangers.

7. The fermentation tank apparatus according to claim 1, characterized in that, The bottom cover has an ellipsoidal structure. The gas distributor includes a straight pipe section that runs through the bottom cover and an annular pipe section that connects to the straight pipe section and is located inside the bottom cover. The annular pipe section has multiple gas outlet holes evenly distributed along its circumference.

8. The fermentation tank apparatus according to claim 1 or 6, characterized in that, The tank body is a cylindrical structure with a height-to-diameter ratio of 1.0-3.0 and an inner diameter-to-outer diameter ratio of 0.9-1.0; the stirring shaft is a cylindrical structure with a diameter-to-tank diameter ratio of 0.02-0.

05.

9. The fermentation tank apparatus according to claim 6, characterized in that, The ratio of the paddle spacing to the tank height is 0.2-0.

5. The paddle spacing is the distance between the bottom and middle agitator paddles or the distance between the middle and top agitator paddles.

10. The fermentation tank apparatus according to claim 7, characterized in that, The annular section and the straight section of the gas distributor have the same diameter. The annular section is located directly below the bottom stirring paddle. The ratio of the diameter of the annular section to the diameter of the tank is 0.2-0.

4. The number of air outlets is 30-60. The air outlets are circular holes with a diameter of 1mm-5mm.

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