External-circulation efficient energy-saving high-viscosity material fermentation system and use method thereof

Abstract

The invention relates to an external-circulation high-efficiency energy-saving high-viscosity material fermentation system and a use method thereof. The system comprises a fermentation tank, an emulsification shear pump, a buffer tank, a screw pump, a distributor and a static mixer, the fermentation tank is connected with the emulsification shear pump through a fermentation discharge pipe, the emulsification shear pump is connected with the buffer tank through a homogeneous feed pipe, the buffer tank is connected with the screw pump through a buffer material pipe, the screw pump is connected with the distributor through a pumping material pipe, and the static mixer is connected with the screw pump. The distributor is connected with the static mixer through a material distribution pipe; the static mixer is connected with the fermentation tank through a material return pipe; the fermentation tank, the buffer tank and the distributor are all connected with the air supply mechanism, and the fermentation tank and the emulsification shear pump are both connected with the disinfection mechanism. The use method of the fermentation system comprises a disinfection stage, an early fermentation stage and internal and external circulation linkage of fermentation. According to the method, the energy consumption of the fermentation process is effectively reduced, the yield of single-batch exopolysaccharides is greatly increased, and the productivity is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a device for high-viscosity material fermentation, belonging to the technical field of microbial fermentation. BACKGROUND

[0002] Industrialized production of microbial extracellular polysaccharides EPS has xanthan gum, pullulan, gellan gum, welan gum, curdlan, sordarin gum, triose gum and psa gum. Except for curdlan, which is a low-viscosity material fermentation, the other several kinds belong to high-viscosity material fermentation. The apparent viscosity of the fermentation broth gradually increases with the fermentation period, and the viscosity is generally 5000-15000 mPa.s, and the gum content is usually 1.7%-10%. Compared with the fermentation of amino acids and organic acids in the same fermentation industry, the content of the target product of the high-viscosity material fermentation is much lower, and the volume of the fermentation tank is also smaller, with a difference of more than 3 times, and the power consumption per unit volume is generally not less than 2.0.

[0003] The fermentation process of high-viscosity material faces a series of difficulties due to the physical properties of the material such as high viscosity, non-Newtonian fluid behavior, and large mass transfer resistance:

[0004] 1. High viscosity leads to poor flowability, making mixing and mass transfer difficult. Traditional stirring cannot uniformly mix, resulting in low oxygen / nutrient / heat transfer efficiency and the formation of local concentration gradients or dead zones.

[0005] 2. Dissolved oxygen DO control is complex. High viscosity hinders the dissolution and diffusion of oxygen, which can easily lead to oxygen deficiency for these high-viscosity material fermentations that belong to aerobic fermentation.

[0006] 3. Heat transfer and temperature control lag. High-viscosity materials have poor thermal conductivity, and stirring heat and biological metabolic heat are not easily dissipated, making it easy to form local overheating conditions.

[0007] 4. Inhibition of cell growth and metabolism. High-viscosity environment may affect the normal metabolism of the cells, and the uptake of nutrients is hindered.

[0008] 5. Difficulty in online monitoring and process control. Using traditional pH, DO, etc. sensors, the probe surface is easily adhered by the material, leading to signal attenuation or distortion.

[0009] To solve the above three difficulties, the current fermentation generally adopts the following measures: one is to increase the stirring speed and the stirring diameter, the former can provide higher shear rate, increase the turbulence and mass transfer and oxygen transfer efficiency, and the latter can increase the stirring area and improve the system circulation, reducing the "dead zone"; two is to increase the tank height-diameter (H:D) ratio to 3-4, which is beneficial to delay the mixing bubble residence time and increase the dissolved oxygen effect.

[0010] The industrialization reality problem brought by the above method is: according to the stirring power calculation formula P=Np pn 3 d 5 , increasing the rotational speed n and the diameter d, the stirring transmission power P is sharply increased, the energy consumption is increased, and the cost is increased, and in order to obtain a larger shear rate, the unit volume power consumption ratio is more than 2.0, and a super large power motor needs to be configured, which becomes an important limiting factor for the development of large-scale fermentation tanks for high-viscosity materials. Limited by materials, the stirring transmission power has a limit and cannot be increased indefinitely. In order to improve the dissolved oxygen, the fine high tank with a height-diameter ratio of more than 2.8 is widely used, and the vibration and shaking caused by the superposition of many factors during operation cause safety problems from time to time, which has been criticized by the industry. SUMMARY

[0011] The present application aims at the existing technical problems of high-viscosity material fermentation, and provides an external circulation high-efficiency energy-saving high-viscosity material fermentation system with high fermentation efficiency, large fermentation scale, low production cost and high efficiency and energy saving, and also provides a use method of the system.

[0012] In order to achieve the above-mentioned purpose, the external circulation high-efficiency energy-saving high-viscosity material fermentation system of the present application adopts the following technical scheme.

[0013] The system comprises a fermentation tank, an external circulation device, a air supply mechanism and a disinfection mechanism, the fermentation tank is a gas-tight container; the external circulation device comprises an emulsification shearing pump, a buffer tank, a screw pump, a distributor and a static mixer, the discharge port of the fermentation tank is connected with the feed inlet of the emulsification shearing pump through a fermentation discharge pipe, the discharge port of the emulsification shearing pump is connected with the feed inlet of the buffer tank through a homogenization feeding pipe, the discharge port of the buffer tank is connected with the feed inlet of the screw pump through a buffer material pipe, the discharge port of the screw pump is connected with the feed inlet of the distributor through a pumping material pipe, the discharge port of the distributor is connected with the feed inlet of the static mixer through a distribution material pipe, and the discharge port of the static mixer is connected with the return material port of the fermentation tank through a return pipe; the fermentation tank, the buffer tank and the distributor are connected with the air supply mechanism, and the fermentation tank and the emulsification shearing pump are connected with the disinfection mechanism; a stirring device is arranged in the fermentation tank.

[0014] A stop valve is arranged on each of the fermentation discharge pipe, the homogenization feeding pipe, the buffer material pipe, the pumping material pipe and the return pipe.

[0015] The stirring device comprises a driving mechanism and a stirring shaft, the driving mechanism is arranged at the top of the fermentation tank, the stirring shaft is connected with the driving mechanism, the part of the stirring shaft in the fermentation tank is provided with an axial flow stirring paddle and a radial flow stirring paddle, the radial flow stirring paddle is below the axial flow stirring paddle, and the axial flow stirring paddle is arranged in layers from top to bottom on the stirring shaft. The driving mechanism drives the stirring shaft to rotate, the axial flow stirring paddle and the radial flow stirring paddle rotate together with the stirring shaft to realize the stirring of the material. The axial flow stirring paddle is an inclined blade paddle, and the inclined blade paddle has 6 blades.

[0016] The air inlet pipe is connected with the air feeding mechanism and the sterilization mechanism, and the control valve and the flow meter are arranged on the air inlet pipe; the outlet of the air inlet pipe inside the fermentation tank is trumpet-shaped and faces downward and is below the stirring device.

[0017] The top of the fermentation tank is provided with the feeding port, the return material port, the air inlet and the air outlet, and the bottom is provided with the discharging port and the air inlet pipe; the return material port is connected with the discharging port of the static mixer through the return material pipe, the discharging port is connected with the feeding port of the emulsifying shear pump through the discharging pipe, the discharging pipe is used for feeding the emulsifying shear pump, the return material pipe is used for feeding the static mixer to the fermentation tank, the air inlet is connected with the air feeding mechanism through the stop valve, and the fermentation tank is kept in the positive pressure state, so that the fermentation liquid is discharged from the fermentation tank.

[0018] Four groups of baffles are arranged on the inner wall of the fermentation tank, the baffles are distributed in the circumferential direction of the inner wall, each group is composed of upper and lower parts, and the baffles are in a wave shape.

[0019] The distributor is provided with the feeding port, the air inlet and the discharging port, the feeding port of the distributor is connected with the discharging port of the screw pump, the air inlet of the distributor is connected with the air feeding mechanism, and the discharging port of the distributor is connected with the feeding port of the static mixer,

[0020] The air feeding mechanism adopts the sterile air pipeline, the fermentation tank, the buffer tank and the distributor are respectively connected with the sterile air pipeline through the stop valve, and high-pressure sterile air is independently provided for the fermentation tank, the buffer tank and the distributor.

[0021] The sterilization mechanism is a steam pipeline, the fermentation tank and the emulsifying shear pump are respectively connected with the steam pipeline through the stop valve, high-temperature steam is independently provided in the fermentation tank and the emulsifying shear pump, and the sterilization effect is realized.

[0022] The use method of the high-viscosity material fermentation system includes a sterilization stage, a fermentation early stage and a fermentation internal and external circulation linkage stage.

[0023] (1) The sterilization stage:

[0024] The fermentation tank is subjected to air sterilization through the sterilization mechanism (steam pipeline), and after the air sterilization is completed, the fermentation medium is put into the fermentation tank for actual sterilization;

[0025] Before the use of the external circulation device (into the fermentation internal and external circulation linkage stage), the air sterilization mechanism is used to sterilize, the stop valve between the emulsification shear pump and the sterilization mechanism (steam pipeline) is opened, the stop valves on the homogenization feeding pipe, the buffer material pipe and the pumping material pipe are opened, the blowdown port of the emulsification shear pump is opened, the stop valve between the buffer tank and the air supply mechanism (sterile air pipeline) is opened, the rear end exhaust plug (small exhaust) is opened, the blowdown port of the buffer tank is opened; the rear end exhaust plug (small exhaust) of the stop valve on the buffer material pipe is opened, the rear end exhaust plug (small exhaust) of the stop valve on the pumping material pipe is opened, the front end exhaust plug (small exhaust) of the stop valve on the back material pipe is opened, and the steam is sequentially introduced into the emulsification shear pump, the buffer tank, the screw pump, the distributor and the static mixer for sterilization. After sterilization for 30 minutes, all valves are closed, and at the same time, the buffer tank is filled with air through the air supply mechanism (opening the stop valve between the buffer tank and the sterile air pipeline), and the pressure in the buffer tank is maintained at 0.1 MPa;

[0026] (2) Fermentation early stage:

[0027] After the fermentation medium in the fermentation tank is inoculated and cooled, the pressure in the fermentation tank is adjusted to 0.05 MPa by the air supply mechanism, the DO electrode is calibrated to 100%, the ventilation volume is 0.35 V / V.m for 0-12 hours, the ventilation volume is adjusted to 0.4 V / V.m for 13-24 hours, and the stirring speed is maintained at 70 r / min.

[0028] (3) Fermentation internal and external circulation linkage stage:

[0029] After fermentation for 24 hours, the fermentation tank 1 is linked with the external circulation device;

[0030] First, stop the air supply to the bottom of the fermentation tank and the buffer tank (close the stop valve on the air inlet pipe between the fermentation tank and the sterile air pipeline, and close the stop valve between the buffer tank and the sterile air pipeline), then open the stop valves on the fermentation discharge pipe, the homogenization feeding pipe, the buffer material pipe, the pumping material pipe, the distribution material pipe and the back material pipe, so that the fermentation broth enters the emulsification shear pump, the rotation speed of the emulsification shear pump is controlled at 1200 rpm, and the flow rate is 1-5 m 3 / h, the homogenized fermentation broth after the emulsification shear pump enters the buffer tank, the screw pump is started when the fermentation broth reaches 2 / 3 of the volume of the buffer tank, the fermentation broth is sent into the distributor by the screw pump, then enters the static mixer from the distributor, and finally flows back to the fermentation tank through the back material pipe;

[0031] The sampling port of the static mixer is sampled to analyze the dissolved oxygen of the shear-mixed fermentation broth, the opening degree of the stop valve between the distributor and the air supply mechanism (sterile air pipeline) is adjusted to adjust the amount of air entering the distributor to meet the needs of the internal and external circulation linkage of the fermentation.

[0032] Maintain the pressure in the fermenter 0.02-0.05MPa, until the residual sugar in the fermentation broth is less than 0.2%, terminate the fermentation.

[0033] Under the same conditions, the technical index, average energy consumption and average dissolved oxygen in the middle and late stages of the xanthan gum fermentation using the system of the application are superior to those of the general fermenter.

[0034] The application connects the fermenter with the external circulation device to form a fermentation combination, provides high dissolved oxygen rate and high shear rate by the external circulation device, completes the mixing of the nutrient components in the fermentation broth by the external emulsifying shear pump, completes the mixing of the fermentation broth and air by the external static mixer, and completes the intensive mixing in a controllable state in a short time to enter the fermenter again, so that the stirring function in the fermenter is weakened correspondingly, the energy consumption of the fermentation process is effectively reduced, the yield of the exocellular polysaccharide of a single batch is greatly improved, the productivity is greatly improved, a train of thought for realizing the large-scale of the fermenter is provided, and the large-scale production of the exocellular polysaccharide is promoted. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the external circulation high-efficiency energy-saving high-viscosity material fermentation system of the application.

[0036] In the figure: 1. Fermenter, 2. Emulsifying shear pump, 3. Buffer tank, 4. Screw pump, 5. Distributor, 6. Static mixer, 7. Stop valve;

[0037] 8. Stirring shaft, 9. Baffle group, 10. Axial flow stirring paddle, 11. Radial flow stirring paddle, 12. Baffle, 13. Air inlet pipe, 14. Feeding port, 15. Discharge port, 16. Discharge port, 17. Return port, 18. Feeding port, 19. Discharge port, 20. Blowdown port, 21. Feeding port, 22. Discharge port, 23. Blowdown port, 24. Air inlet pipe, 25. Feeding port, 26. Discharge port, 27. Feeding port, 28. Air inlet port, 29. Discharge port, 30. Feeding port, 31. Discharge port, 32. Fermentation discharge pipe, 33. Homogenizing feeding pipe, 34. Buffer material pipe, 35. Pumping material pipe, 36. Distributing material pipe, 37. Return pipe;

[0038] 38. Sterile air pipeline, 39. Steam pipeline. DETAILED DESCRIPTION

[0039] To make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0040] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0041] The external circulation high-efficiency energy-saving high-viscosity material fermentation system of the present application is a fermentation assembly composed of a fermentation tank and an external circulation device. Figure 1 As shown in the figure, it includes a fermentation tank 1, an emulsifying shearing pump 2, a buffer tank 3, a screw pump 4, a distributor 5 and a static mixer 6. The discharge port 16 at the bottom of the fermentation tank 1 is connected to the feed port 18 of the emulsifying shearing pump 2 through a fermentation discharge pipe 32, the discharge port 19 of the emulsifying shearing pump 2 is connected to the feed port 21 at the top of the buffer tank 3 through a homogenizing feeding pipe 33, the discharge port 22 at the bottom of the buffer tank 3 is connected to the feed port 25 of the screw pump 4 through a buffer material pipe 34, the discharge port 26 of the screw pump 4 is connected to the feed port 27 of the distributor 5 through a pumping material pipe 35, the discharge port 29 of the distributor 5 is connected to the feed port 30 of the static mixer 6 through a distribution material pipe 36, and the discharge port 31 of the static mixer 6 is connected to the top return port of the fermentation tank 1 through a return pipe 37.

[0042] An agitator shaft 8 for stirring the material is arranged in the fermentation tank 1, the agitator shaft 8 is provided with axial flow stirring paddles 10 and radial flow stirring paddles 11, the axial flow stirring paddles 10 are arranged in multiple layers, and the radial flow stirring paddles 11 are arranged at the bottommost. The agitator shaft 8 is connected with a stirring motor installed at the top of the fermentation tank 1. Two layers of baffle groups 9 are arranged on the inner wall of the fermentation tank 1, each group has four baffles 12, which are distributed in a circumferential symmetry on the inner wall of the fermentation tank 1, and the baffles 12 are in a wave shape.

[0043] A feed port 14, a return port 17, an air inlet and an air outlet are arranged at the top of the fermentation tank 1. The fermentation material enters the fermentation tank 1 through the feed port 14. The return port 17 is connected with the return pipe 37 through a stop valve, and the return pipe 37 is connected with the discharge port 30 of the static mixer 6. The air inlet is connected with a sterile air pipeline 38 through a stop valve, and when the stop valve is opened, the fermentation tank 1 is filled with air through the air inlet, so that the fermentation tank 1 is kept in a positive pressure state, and the fermentation liquid flows out of the fermentation tank 1.

[0044] The bottom of the fermentation tank 1 is provided with an air inlet pipe 13 extending into it, the air inlet pipe 13 is connected with the sterile air pipeline 38 and a steam pipeline 39, and stop valves 7 are arranged on the sterile air pipeline 38 and the steam pipeline 39 respectively to adjust the air inlet amount. A flow meter can also be arranged to check the flow rate. The outlet of the air inlet pipe 13 inside the fermentation tank 1 is in a trumpet shape, faces downward and is located in the center of the fermentation tank 1, and is below the bottommost radial flow stirring paddles 11 of the agitator shaft 8.

[0045] The bottom of the fermentation tank 1 is provided with a discharge port 15 and a discharge port 16. The discharge port 15 is provided with a stop valve. The discharge port 16 is connected with a fermentation discharge pipe 32 through a stop valve.

[0046] The emulsification shear pump 2 is provided with a feed inlet 18, a discharge outlet 19 and a blowdown outlet 20. The feed inlet 18 is connected to the fermentation discharge pipe 32 and the steam pipe 39 through a stop valve respectively, and is connected to the bottom discharge outlet 16 of the fermentation tank 1 and the steam pipe. The material pipe and the steam pipe are respectively provided with a stop valve to control the start and stop of the pipe. The discharge outlet 19 is connected to the homogenizing feeding pipe 33 through a stop valve, and the homogenizing feeding pipe 33 is connected to the feed inlet 21 at the top of the buffer tank 3 through a stop valve.

[0047] The top of the buffer tank 3 is provided with a feed inlet 21 and an air inlet pipe 24, and the bottom is provided with a discharge outlet 22 and a blowdown outlet 23. The feed inlet 21 is connected to the discharge outlet 19 of the emulsification shear pump 2 through a stop valve. The air inlet pipe 24 is connected to the sterile air pipe 38. The discharge outlet 22 is connected to the buffer material pipe 34 through a stop valve, and the buffer material pipe 34 is connected to the feed inlet 25 of the screw pump 4. The top of the buffer tank 3 is provided with a pressure gauge to display the gas pressure in the tank.

[0048] The screw pump 4 is provided with a feed inlet 25 and a discharge outlet 26, which are respectively connected to the pipe structure 7. The feed inlet 25 is connected to the discharge outlet 22 of the buffer tank 3. The discharge outlet 26 is connected to the pumping material pipe 35 through a stop valve, and the pumping material pipe 35 is connected to the feed inlet 27 of the distributor 5.

[0049] The distributor 5 is provided with a feed inlet 27, an air inlet 28 and a discharge outlet 29, which are respectively connected to the pipe structure 7. The feed inlet 27 is connected to the discharge outlet 26 of the buffer tank 4. The air inlet 28 is connected to the sterile air pipe 38, and a stop valve is arranged in the air pipe 38 to adjust the air inlet amount. The discharge outlet 29 is connected to the feed inlet 30 of the static mixer 6 through the distribution material pipe 36.

[0050] The static mixer 6 is provided with a feed inlet 30 and a discharge outlet 31. The feed inlet 30 is connected to the discharge outlet 26 of the distributor 5, and the discharge outlet 31 is connected to the back feeding port 17 of the fermentation tank 1 through the back feeding pipe 37.

[0051] The discharge outlet 16 at the bottom of the fermentation tank 1 is connected to the feed inlet 18 of the emulsification shear pump 2 through the fermentation discharge pipe 32. The discharge outlet 19 of the emulsification shear pump 2 is connected to the feed inlet 21 at the top of the buffer tank 3 through the homogenizing feeding pipe 33. The discharge outlet 22 at the bottom of the buffer tank 3 is connected to the feed inlet 25 of the screw pump 4 through the buffer material pipe 34. The discharge outlet 26 of the screw pump 4 is connected to the feed inlet 27 of the distributor 5 through the pumping material pipe 35. The discharge outlet 29 of the distributor 5 is connected to the feed inlet 30 of the static mixer 6 through the distribution material pipe 36. The discharge outlet 31 of the static mixer 6 is connected to the top back feeding port 14 of the fermentation tank 1 through the back feeding pipe 37.

[0052] The fermentation process of the system for high viscosity material includes four stages: sterilization of the fermentor, pre-fermentation, air sterilization of the external circulation device, and linkage of internal and external circulation.

[0053] 1. Sterilization of the fermentor

[0054] The fermentor 1 is sterilized by air, the stop valve between the fermentor 1 and the steam pipeline 39 is opened, steam enters the fermentor 1 through the air inlet 13, and the air outlet at the top of the fermentor 1 is opened to sterilize the fermentor 1 by steam. The process parameters are controlled in the same way as the current general fermentation process.

[0055] After the air sterilization, the fermentation medium is put into the fermentor 1 through the feed inlet 14 for actual sterilization. The actual sterilization is carried out in batch or continuously according to the actual need.

[0056] The external circulation device is sterilized by air before use, that is, the sterilization of the external circulation device by steam starts when the linkage of the fermentor 1 and the external circulation device is entered (see the linkage of internal and external circulation). The stop valve between the emulsifying shear pump 2 and the steam pipeline 39 is opened, the stop valve on the homogenizing feed pipeline 33 between the emulsifying shear pump 2 and the buffer tank 3 is opened, the blowdown port 20 of the emulsifying shear pump 2 is opened, the rear end exhaust plug of the stop valve between the buffer tank 3 and the sterile air pipeline 38 is opened (small exhaust is carried out), the blowdown port 23 of the buffer tank 3 is opened, the stop valve on the buffer material pipeline 34 between the buffer tank 3 and the screw pump 4 and the rear end exhaust plug of the stop valve are opened (small exhaust is carried out), the stop valve on the pumped material pipeline 35 between the screw pump 4 and the distributor 5 and the rear end exhaust plug of the stop valve are opened (small exhaust is carried out), the front end exhaust plug of the stop valve on the return material pipeline 37 between the static mixer 6 and the fermentor 1 is opened (small exhaust is carried out), and steam enters the emulsifying shear pump 2, the buffer tank 3, the screw pump 4, the distributor 5 and the static mixer 6 in sequence for sterilization, and the sterilization time is 30 min. At this time, all the valves are closed from back to front (static mixer 6 to emulsifying shear pump 2), and the stop valve between the buffer tank 3 and the sterile air pipeline 38 is opened to fill the buffer tank 3 with air, so that the pressure of the entire circulation system is maintained at 0.1 MPa.

[0057] 2. Pre-fermentation:

[0058] After the fermentation medium in the fermentor 1 is cooled, inoculation is carried out, the stop valve 7 between the air inlet 13 at the bottom of the fermentor 1 and the sterile air pipeline 38 is opened, the fermentor 1 is filled with air, the pressure in the fermentor 1 is adjusted to 0.05 MPa, the DO electrode is calibrated to 100%, the ventilation volume is 0.35 V / V.m for 0-12 h, it is adjusted to 0.4 V / V.m for 13-24 h, and the rotating speed of the stirring shaft 8 is maintained at 70 r / min.

[0059] 0-24h is the early fermentation stage, in this stage the apparent viscosity of the fermentation broth begins to increase, the dissolved oxygen level decreases significantly; 18h before the view observed by the sight glass seen liquid surface more calm and uniform small bubbles gradually disappear, bubble coalescence increased, slowly move to the shaft center and the tank wall after the drum out, the "dead zone" in the tank stirring began to appear, DO decreased to 30%, 18-24h bubble and dead zone significantly strengthened, the splashing of the fermentation broth on the tank wall above the liquid surface constantly down, 24h after the DO value is 0.

[0060] 3. Fermentation internal and external circulation linkage

[0061] After fermentation to 24h, into the fermentation tank 1 and external circulation device linkage stage. After the external circulation device starts, the stop valve 7 on the air inlet pipe 13 between the fermentation tank 1 and the sterile air pipeline 38 is adjusted or closed.

[0062] The stop valve between the buffer tank 3 and the sterile air pipeline 38 is closed, and the stop valve on the fermentation outlet pipe 32 between the fermentation tank 1 and the emulsification shear pump 2 is opened. The stop valve on the homogenization feeding pipe 33 between the emulsification shear pump 2 and the buffer tank 3 is opened, the stop valve on the buffer material pipe 34 between the buffer tank 3 and the screw pump 4 is opened, the stop valve on the pumping material pipe 35 between the screw pump 4 and the distributor 5 is opened, the stop valve on the distribution material pipe 36 between the distributor 5 and the static mixer 6 is opened, and the stop valve on the return pipe 37 between the static mixer 6 and the fermentation tank 1 is opened. The fermentation broth is made to enter the emulsification shear pump 2 through the fermentation tank outlet 16, the rotation speed of the emulsification shear pump 2 is controlled at 1200 rpm, and the flow rate is 1-5 m 3 / h, which can be adjusted. The homogenized fermentation broth enters the buffer tank 3, and when the fermentation broth reaches 2 / 3 of the volume of the buffer tank 3, the screw pump 4 is started. The fermentation broth is sent into the distributor 5 through the screw pump 4, and then enters the static mixer 6 through the distributor 5, and finally flows back to the fermentation tank 1 through the return pipe 37.

[0063] The sampling port of the static mixer 6 is sampled in time to analyze the dissolved oxygen of the shear-mixed fermentation broth. The air amount entering the distributor 5 is adjusted by adjusting the opening degree of the stop valve between the distributor 5 and the sterile air pipeline 38 to meet the dissolved oxygen needs of the internal and external circulation linkage.

[0064] After the start of the linkage stage of the fermentation tank 1 and the external circulation device, the stop valve 7 between the air inlet pipe 13 at the bottom of the fermentation tank 1 and the sterile air pipeline 38 can be adjusted or closed according to the dissolved oxygen condition of the fermentation broth, the air inlet of the fermentation tank 1 at the top is opened to charge air into the fermentation tank 1, the pressure in the fermentation tank 1 is maintained at 0.02-0.05 MPa, until the residual sugar in the fermentation broth is less than 0.2%, and the fermentation is terminated.

[0065] After the fermentation is completed, air is filled into the fermenter 1 through the air inlet on the top of the fermenter 1 to keep the fermenter 1 in a positive pressure state, so that the fermentation liquid flows out from the discharge port 15 at the bottom of the fermenter 1.

[0066] The application will be further described in conjunction with specific application examples. However, the protection scope of the application is not limited to this. The technical solutions of the application examples are described clearly and completely. Obviously, the described application examples are part of the embodiments of the application, rather than all the embodiments. Based on the described embodiments of the application, all other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the protection scope of the application.

[0067] Unless otherwise defined, the technical terms or scientific terms used herein should be understood as the common meanings thereof by those of ordinary skill in the art to which the application belongs.

[0068] In the following examples, a 3000L fermenter is taken as an example to carry out batch fermentation of welan gum. The culture medium used in the fermentation process is as follows:

[0069] Seed culture medium: yeast extract 1g / L, KH2PO3·3H2O 2g / L, MgSO4·7H2O 0.1g / L, protein peptone 0.5g / L, sucrose 20g / L, purified water to volume, pH 7.2.

[0070] Fermenter culture medium: KH2PO3·3H2O 2g / L, MgSO4·7H2O 0.3g / L, soybean powder 5g / L, sucrose 40g / L, soybean oil 1.5mL / L, softened water to volume, pH 7.5.

[0071] The following examples take the fermentation of alkali-producing bacillus for producing welan gum as an example to illustrate the fermentation process of the high-viscosity material fermentation equipment combination described in the application. However, the protection scope of the application is not limited to this. Other microorganisms producing extracellular polysaccharides are also applicable to the fermentation process described in the application.

[0072] Comparative Example 1

[0073] This comparative example uses a general fermenter available in the art as a comparative example of Example 1.

[0074] (1) Seed liquid culture in a shake flask:

[0075] Four 500mL shake flasks are filled with 100mL of welan gum seed culture medium, which is sterilized and cooled, and then 200μL of alkali-producing bacillus strain is taken from a glycerol freezing tube and cultured at a temperature of 28.0±1.0℃ and a shaking speed of 220±10rpm for about 24 hours. At this time, no foreign bacteria are observed under a microscope, and the OD600 value of the bacterial liquid reaches 2-3, obtaining a seed liquid.

[0076] (2) Primary seed tank culture:

[0077] A 10 L stainless steel tank was filled with 7.5 L of seed culture medium and sterilized. Before inoculation, the rotation speed in the tank was adjusted to 300 rpm, the aeration amount was 4 L / min, and the temperature was 28°C. The seed liquid prepared in step (1) with an OD600 value of 2-3 was inoculated into the tank at a volume of 5% (v / v) (ring inoculation), and after the DO electrode was calibrated to 100%, fermentation was started. The fermentation was continued until 12 hours, at which time the OD600 value was 2-3, to obtain the primary seed tank fermentation liquid.

[0078] (3) Secondary seed tank culture:

[0079] A 500 L stainless steel tank was filled with 360 L of seed culture medium and sterilized. Before inoculation, the rotation speed in the tank was adjusted to 300 rpm, the aeration amount was 180 L / min, and the temperature was 28°C. The primary seed tank fermentation liquid prepared in step (2) with an OD600 value of 2-3 was inoculated into the tank through a transfer pipe at a volume of 2% (v / v), and after the DO electrode was calibrated to 100%, fermentation was started. The fermentation was continued until 12 hours, at which time the OD600 value was 2-3, to obtain the secondary seed tank fermentation liquid.

[0080] (4) Fermentation base culture:

[0081] A 3000 L fermentation tank (φ1100, motor power 7.5 KW, rated current 16 A, same below) was filled with 1800 L of fermentation tank culture medium and sterilized. The stirring module described in the application was used, the blade diameter was 0.35 times the tank diameter, and before inoculation, the rotation speed was adjusted to 250 r / min, the aeration amount was 900 L / min, and the temperature was 30°C. The secondary seed tank fermentation liquid prepared in step (2) with an OD600 value of 2-3 was inoculated into the fermentation tank through a transfer pipe at a volume of 10% (v / v), and after the DO electrode was calibrated to 100%, fermentation was started. The rotation speed was adjusted according to the dissolved oxygen, and the fermentation was stopped when the base sucrose in the fermentation medium was consumed, at which time the DO rebounded quickly. The fermentation period was 60 h, and the average current was 8.47 A.

[0082] After the fermentation was completed, about 1800 L of fermentation liquid was obtained, and the Welan gum content was 13.9 g / L.

[0083] Comparative Example 2

[0084] This comparative example used an existing general fermentation tank as a comparative example of Example 2.

[0085] (1) Shake flask seed liquid culture:

[0086] In 4 500mL shake flasks, 100mL of Welan gum seed medium was filled and sterilized. After cooling, 200μL of the frozen glycerol tube was removed and cultured at 28.0±1.0℃ and a shaking speed of 220±10rpm for 24 hours. At this time, no impurities were observed under a microscope and the OD600 value of the seed liquid was 2-3, obtaining the seed liquid.

[0087] (2) Primary seed tank culture:

[0088] A 10L stainless steel tank was filled with 7.5L of seed medium and sterilized. Before inoculation, the rotation speed of the tank was adjusted to 300r / min, the aeration amount was 4L / min, and the temperature was 28℃. The seed liquid prepared in step (1) with an OD600 value of 2-3 was inoculated into the tank (fire ring inoculation) at a volume of 5% (v / v). After inoculation was completed and the DO electrode was calibrated to 100%, fermentation was started. After 12 hours, the OD600 value was 2-3, obtaining the primary seed tank fermentation liquid.

[0089] (3) Secondary seed tank culture:

[0090] A 500L stainless steel tank was filled with 360L of seed medium and sterilized. Before inoculation, the rotation speed of the tank was adjusted to 300r / min, the aeration amount was 180L / min, and the temperature was 28℃. The primary seed tank fermentation liquid prepared in step (2) with an OD600 value of 2-3 was inoculated into the tank through a transfer pipe at a volume of 2% (v / v). After inoculation was completed and the DO electrode was calibrated to 100%, fermentation was started. After 12 hours, the OD600 value was 2-3, obtaining the secondary seed tank fermentation liquid.

[0091] (4) Fermentation base culture:

[0092] A 3000L fermentation tank was filled with 1800L of fermentation medium and sterilized. The fermentation tank used the stirring module described in the application, the blade diameter was 0.6 times the diameter of the tank, and the rotation speed was adjusted to 100r / min, the aeration amount was 900L / min, and the temperature was 30℃ before inoculation. The secondary seed tank fermentation liquid prepared in step (2) with an OD600 value of 2-3 was inoculated into the fermentation tank through a transfer pipe at a volume of 10% (v / v). After inoculation was completed and the DO electrode was calibrated to 100%, fermentation was started. After the base sucrose in the fermentation medium was consumed, fermentation was stopped. At this time, the DO rebounded quickly, which took 60h, and the average current was 5.64A.

[0093] After fermentation was completed, about 1800L of fermentation liquid was obtained, and the Welan gum content was 14.2g / L.

[0094] Example 1

[0095] In this example, the high-viscosity material fermentation system of the application was used.

[0096] (1) Seed liquid culture in shake flask: the specific process was the same as that in the seed liquid culture in shake flask in Comparative Example 1.

[0097] (2) Primary seed tank culture: the specific process was the same as that in the primary seed tank culture in Comparative Example 1.

[0098] (3) Secondary seed tank culture: the specific process was the same as that in the secondary seed tank culture in Comparative Example 1.

[0099] (4) Fermentation base culture:

[0100] In a 3000L fermentation tank, 1800L of fermentation medium was sterilized, the fermentation tank used the stirring module described in the application, the blade diameter was 0.6 times the tank diameter, the rotation speed in the tank was adjusted to 50 rpm, the air flow was 900L / min, and the temperature was 30°C before inoculation. The secondary seed liquid prepared in step (2) with an OD600 value of 2-3 was inoculated into the fermentation tank through a transfer pipe at a volume of 10% (v / v), and after the DO electrode was calibrated to 100%, the fermentation was started. After 24h, the air flow was closed, the external circulation system was started, the fermentation liquid entered the emulsification shear pump through the tank bottom outlet, the shear pump rotation speed was 1500 rpm, the flow rate was 3m3 / h, the homogenized fermentation liquid entered the buffer tank, entered the distributor through the screw pump, the air flow was adjusted and mixed with the fermentation liquid, then entered the static mixer, and finally returned to the tank top return port of the fermentation tank until the base sucrose in the fermentation medium was consumed and the fermentation was stopped. At this time, the DO rebounded quickly, and the time was 60h.

[0101] After the fermentation was completed, the fermentation liquid volume was about 1800L, the welan gum content was 18.9g / L, the average energy consumption of the fermentation tank was 2.0kw, the average energy consumption of the shear pump was 1.0kw, and the average energy consumption of the screw pump was 0.75kw.

[0102] Example 2

[0103] In this example, the high-viscosity material fermentation system of the application was used.

[0104] (1) Seed liquid culture in shake flask: the specific process was the same as that in the seed liquid culture in shake flask in Comparative Example 1.

[0105] (2) Primary seed tank culture: the specific process was the same as that in the primary seed tank culture in Comparative Example 1.

[0106] (3) Secondary seed tank culture: the specific process was the same as that in the secondary seed tank culture in Comparative Example 1.

[0107] (4) Fermentation base culture:

[0108] In a 3000L fermenter, 1800L fermentation medium was sterilized, the fermenter used the stirring module described in the application, the blade diameter was 0.6 times the diameter of the tank, the rotation speed in the tank was adjusted to 50 rpm, the aeration volume was 900L / min, and the temperature was 30℃ before inoculation. The OD600 value of the secondary seed tank fermentation liquid prepared in step (2) was 2-3, which was inoculated into the fermenter through the transfer pipe at 10% (v / v), and the fermentation was started after the DO electrode was calibrated to 100% after inoculation. After 24h, the external circulation was started, the fermentation liquid passed through the tank bottom outlet into the emulsification shear pump, the shear pump rotation speed was 1200rpm, the flow rate was 3m3 / h, the homogenized fermentation liquid passed through the buffer tank, entered the static mixer through the screw pump, and finally returned to the top of the fermenter. When the basic sucrose in the fermentation medium was consumed, the fermentation was stopped, at this time, the DO rebounded quickly, and the time was 60h.

[0109] After the fermentation was completed, about 1800L fermentation liquid was obtained, the welan gum content was 20.1g / L, the average energy consumption of the fermenter was 2.0kw, the average energy consumption of the shear pump was 1.0kw, and the average energy consumption of the screw pump was 0.75kw.

[0110] In summary, the high-viscosity material fermentation equipment combination described in the application is used, large-diameter and low-speed stirring is used in the fermenter, the fermentation is carried out for 24h, when the fermentation liquid has become sticky, only the tank top gas is used to maintain the tank pressure, the lower gas inlet is closed, the external circulation system is started, the sticky layer of the cell outer layer which hinders the exchange of nutrients and gas is torn by the external emulsification shear pump 2, the mixing of the fermentation liquid and air is completed by the external static mixer 6, so as to reduce the working pressure of the stirring module in the fermenter, effectively reduce the energy consumption of the fermentation process, greatly improve the yield of the extracellular polysaccharide per batch, greatly improve the productivity, provide a train of thought for the large-scale fermentation tank, promote the large-scale production of extracellular polysaccharide, bring huge economic benefits to the enterprise, and have good practicability; the height-diameter ratio of the fermenter 1 is reduced according to the needs, which provides a feasible scheme for the development of large-scale fermentation tank, the expansion of fermentation scale, the improvement of fermentation efficiency, and the reduction of production cost.

[0111] The embodiments are preferred embodiments of the application, but the application is not limited to the above embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art without departing from the essential content of the application shall fall within the protection scope of the application.

Claims

1. A high-efficiency and energy-saving fermentation system for high-viscosity materials with external circulation, characterized in that: The fermentation tank, the external circulation device, the air supply mechanism and the sterilization mechanism are included, and the fermentation tank is an airtight container; the external circulation device includes an emulsification shearing pump, a buffer tank, a screw pump, a distributor and a static mixer, the discharge port of the fermentation tank is connected with the feed inlet of the emulsification shearing pump through a fermentation discharge pipe, the discharge port of the emulsification shearing pump is connected with the feed inlet of the buffer tank through a homogenization feeding pipe, the discharge port of the buffer tank is connected with the feed inlet of the screw pump through a buffer material pipe, the discharge port of the screw pump is connected with the feed inlet of the distributor through a pumping material pipe, the discharge port of the distributor is connected with the feed inlet of the static mixer through a distribution material pipe, and the discharge port of the static mixer is connected with the return material port of the fermentation tank through a return pipe; the fermentation tank, the buffer tank and the distributor are connected with the air supply mechanism, and the fermentation tank and the emulsification shearing pump are connected with the sterilization mechanism; a stirring device is arranged in the fermentation tank.

2. The external circulation high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: The fermentation discharge pipe, the homogenization feeding pipe, the buffer material pipe, the pumping material pipe and the return pipe are all provided with stop valves.

3. The external circulation high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: The stirring device includes a driving mechanism and a stirring shaft, the driving mechanism is arranged at the top of the fermentation tank, the stirring shaft is connected with the driving mechanism, the part of the stirring shaft in the fermentation tank is provided with axial flow stirring paddles and radial flow stirring paddles, the radial flow stirring paddles are below the axial flow stirring paddles, and the axial flow stirring paddles are arranged in layers from top to bottom on the stirring shaft.

4. The external circulation high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: The bottom of the fermentation tank is provided with an air inlet pipe, one side of the air inlet pipe is connected with the air supply mechanism and the other side is connected with the sterilization mechanism, and the air inlet pipe is provided with a control valve and a flow meter; the outlet of the air inlet pipe inside the fermentation tank is trumpet-shaped and faces downward and is below the stirring device.

5. The external loop high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: The top of the fermentation tank is provided with a feed inlet, a return material port, an air inlet and an exhaust port, and the bottom is provided with a discharge port and an air inlet pipe; the return material port is connected with the discharge port of the static mixer through the return pipe, the discharge port is connected with the feed inlet of the emulsification shearing pump through a discharge pipe, the discharge pipe is used for feeding the emulsification shearing pump, the return pipe is used for feeding the static mixer to the fermentation tank, and the air inlet is connected with the air supply mechanism through a stop valve.

6. The external loop high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: Four groups of baffles are arranged on the inner wall of the fermentation tank, the baffles are distributed in the circumferential direction of the inner wall symmetrically, each group is composed of two parts arranged above and below, and the baffles are in a wave shape.

7. The external loop high-efficiency and energy-saving high-viscous material fermentation system according to claim 1, characterized in that: The distributor is provided with a feed inlet, an air inlet and a discharge port, the feed inlet of the distributor is connected with the discharge port of the screw pump, the air inlet of the distributor is connected with the air supply mechanism, and the discharge port of the distributor is connected with the feed inlet of the static mixer.

8. The system for fermentation of high viscous material of claim 1 wherein: The air supply mechanism adopts a sterile air pipeline, the fermentation tank, the buffer tank and the distributor are respectively connected with the sterile air pipeline through stop valves, and high-pressure sterile air is independently provided for the fermentation tank, the buffer tank and the distributor.

9. The external loop high efficient and energy saving high viscous material fermentation system as claimed in claim 1, characterized in that: The sterilization mechanism is a steam pipeline, and the fermentation tank and the emulsification shearing pump are respectively connected with the steam pipeline through stop valves.

10. The use of the external loop high efficiency and energy saving high viscous material fermentation system according to any one of claims 1-9, characterized in that: The process includes a sterilization stage, a fermentation early stage and a fermentation internal and external circulation linkage stage: (1) the sterilization stage: The fermentation tank is subjected to air sterilization through the sterilization mechanism, and after the air sterilization is completed, a fermentation medium is put into the fermentation tank for actual sterilization; Before the use of the external circulation device, the emptying and sterilizing mechanism is used to empty and sterilize, the stop valve between the emulsification and shearing pump and the emptying and sterilizing mechanism is opened, the stop valves on the homogenizing feeding pipe, the buffer material pipe and the pumped material pipe are opened, the blow-off port of the emulsification and shearing pump is opened, the rear end exhaust plug of the stop valve between the buffer tank and the air feeding mechanism is opened, the blow-off port of the buffer tank is opened, the rear end exhaust plug of the stop valve on the buffer material pipe is opened, the rear end exhaust plug of the stop valve on the pumped material pipe is opened, the front end exhaust plug of the stop valve on the back material pipe is opened, the steam is sequentially introduced into the emulsification and shearing pump, the buffer tank, the screw pump, the distributor and the static mixer for sterilization, all the valves are closed after 30 minutes of sterilization, and the buffer tank is inflated by the air feeding mechanism to maintain the pressure in the buffer tank at 0.1 MPa; (2) Early stage of fermentation: After the fermentation medium in the fermenter is inoculated and cooled, the pressure in the fermenter is adjusted to 0.05 MPa by the air feeding mechanism, the DO electrode is calibrated to 100%, the ventilation volume is 0.35 V / V.m in 0-12 hours, the ventilation volume is adjusted to 0.4 V / V.m in 13-24 hours, and the stirring speed is kept at 70 r / min; (3) Fermentation with internal and external circulation linkage: After 24 hours of fermentation, the linkage between the fermenter and the external circulation device is entered; First stop to the fermentation tank bottom and buffer tank air supply, then open fermentation discharge pipe, homogeneous feeding pipe, buffer material pipe, pumping material pipe, distribution material pipe and the return material pipe on the stop valve, make the fermentation broth into emulsification shear pump, the rotation speed control of emulsification shear pump is 1200rpm, the flow rate is 1-5m 3 / h, the fermentation broth after homogenization by emulsification shear pump enters the buffer tank, when the fermentation broth reaches 2 / 3 of the buffer tank volume, start the screw pump, the fermentation broth is sent into the distributor by the screw pump, then enters the static mixer by the distributor, and finally flows back to the fermentation tank through the return material pipe; The sample is taken from the sampling port of the static mixer, the dissolved oxygen of the fermentation liquid after shearing and mixing is analyzed, the opening of the stop valve between the distributor and the air feeding mechanism is adjusted to adjust the air volume introduced into the distributor to meet the dissolved oxygen requirement of the internal and external circulation linkage of fermentation; The pressure in the fermenter is maintained at 0.02-0.05 MPa until the residual sugar in the fermentation liquid is less than 0.2%, and the fermentation is terminated.

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