Key points for attention of fermentation equipment

　　1. Classification of culture media by purpose?
(1) Spore culture medium: Spore culture medium is used for bacterial reproduction of spores. The requirements for this medium are to enable the bacterial strain to germinate and grow quickly, produce a large number of high-quality spores, and not cause bacterial strain variation.
(2) Seed culture medium: Seed culture medium refers to the nutritional composition of seed jars used for shake bottle seed cultivation or industrial production seed cultivation.
(3) Fermentation medium: Fermentation medium contains nutritional components necessary for the rapid growth, reproduction, and synthesis of products by mycelium.
2. Common sterilization methods for culture media?
Chemical sterilization, radiation sterilization, dry heat sterilization (160 ℃ insulation for 1-2 hours), wet heat sterilization, filtration sterilization
3. Definition of Batch Sterilization (Solid Can Sterilization), Preparation Before Sterilization, Operation Process and Three Stages of Sterilization?
Definition: Prepare the culture medium in a fermentation tank, heat it directly with saturated steam to reach the predetermined sterilization temperature and maintain it for a period of time, then cool it down to the fermentation temperature. This sterilization process is called medium tank sterilization or medium batch sterilization (sterilization).
Preparation before sterilization: In order to ensure the success of sterilization, it is particularly important to check the tightness of the fermentation tank, especially the tightness of the valves directly connected to the fermentation tank, in addition to ensuring that the culture medium is dissolved uniformly and does not contain clumps, agglomerates or foreign objects before sterilization of the actual tank. In large fermentation enterprises, it is usually necessary to replace the rubber sealing gasket of the rubber clamping valve directly connected to the fermentation and the PTFE sealing gasket on the stainless steel or copper shell plastic king core globe valve after each batch of fermentation is completed to ensure the tightness of the fermentation tank throughout the entire fermentation cycle.
The three stages of batch sterilization are heating, insulation sterilization, and cooling.
4. Regarding the calculation of time in batch sterilization?
5. Definition, advantages, and 7 key equipment of continuous sterilization. What are the structural characteristics of the heater, maintenance equipment, and cooler?
Definition: The continuous sterilization process of culture medium is to pre sterilize the fermentation tank, continuously heat, insulate, sterilize and cool the culture outside the fermentation tank using efficient equipment, and then continuously enter the sterilized fermentation tank. This sterilization method for culture media is called continuous sterilization, also known as continuous sterilization in factories.
Advantages: (1) Adopting high temperature and rapid sterilization, the material has a short heating time, less damage to nutrients, good quality of the culture medium after continuous sterilization, and a high fermentation unit. (2) Due to the short sterilization time, the utilization rate of the fermentation tank is high. (3) Steam load balance and high boiler utilization. (4) Suitable for automatic control. (5) Reduce labor intensity.
What are the quality standards for sterile air?
(1) Compressed air pressure: Generally, it is required to control the air pressure at the outlet of the air compressor between 0.2 and 0.35 MPa, and there is no need to force the air pressure at the outlet of the compressor to be too high.
(2) Air flow rate: Determine the flow rate of compressed air to be provided based on the overall fermentation tank volume of the fermentation factory or workshop.
(3) The temperature of the air: In order to reduce the relative humidity of the air, it is often necessary to use the method of heating compressed air appropriately. Generally, the temperature of the compressed air entering the fermentation tank is controlled to be about 10 ℃ higher than the fermentation temperature.
(4) Relative humidity: Due to the current use of cellulose paper, PP felt, or cotton as the filtering medium for the air main filter in fermentation factories, the filtration effect will greatly decrease when these filtering media become damp. Therefore, the relative humidity of the compressed air entering the main filter is controlled at 60% to 70%.
(5) Cleanliness: In the fermentation industry, "sterile air" refers to clean air with reduced bacterial content to zero or a cleanliness level of 100 after sterilization treatment, which can meet the requirements of the fermentation industry.
What are the purposes of compressed air pretreatment, cooling calculation, and water removal calculation?
In order to ensure the dryness of the filter medium in the main filter, the water droplets and oil droplets carried in the compressed air should not be affected by moisture and cause the medium to transform and become ineffective. Therefore, before entering the main filter, the water droplets and oil droplets carried in the compressed air should be removed. Water droplets are released due to the phase change of water vapor in the air after being compressed and cooled by a compressor; Oil droplets are carried out by the air from the lubricating oil of the piston ring of the air compressor. If a turbo compressor is used, there will be no oil droplets in the compressor air, and the quality of the gas supply will be greatly improved, but the equipment investment is relatively high. If other types of air compressors are used, the compressed air obtained will contain a small amount of oil droplets. Therefore, compressed air must undergo pre-treatment such as cooling, water removal, and oil removal before entering the air main filter.
What is the equipment process and principles of various devices in the compressed air pretreatment system?
Suction tower → pre filter → air compressor → air storage tank → first cooler → cyclone separator → second cooler → cyclone separator → wire mesh demister → air heater → main filter → air filter on the fermentation tank entering the workshop
9. What are the different classifications of commonly used aerobic fermentation tanks based on their energy input methods and the principles behind each type of fermentation tank?
(1) Mechanical stirring (dominant): Stirring the liquid inside the tank with a stirrer to provide power and achieve the requirements of mass transfer, heat transfer, and liquid mixing.
(2) Airlift fermentation tank: Airlift fermentation tank uses compressed air sprayed from nozzles to push the culture solution up along the guide tube (due to the low liquid density in the rich gas area), circulating from inside to outside or from outside to inside to achieve mixing and mass transfer.
(3) External liquid circulation type: divided into tower type and tank type. It relies on an external circulation pump to stir and mix the fermentation broth, while some use power to transport the culture broth through nozzles located at the top or bottom. Some fermentation tanks are equipped with a Venturi tube at the liquid inlet, which mixes with sterile compressed air or self inhaled sterile air under high-speed liquid flow to achieve ventilation and mixing.
What are the main components of a universal fermentation tank?
Tank mixing device, defoamer, shaft seal, transmission device, heat transfer device, baffle, manhole sight glass, ventilation device, inlet and outlet pipes, and boom pipes
What is the function of the baffle and what are the conditions for a full baffle?
The function of the baffle is to change the flow direction of the stirred liquid, causing it to move longitudinally, thereby eliminating the concave vortex generated in the central part of the liquid surface.
The so-called full baffle condition refers to the condition that baffles are added in the tank to make the vortex disappear basically, or the minimum baffle condition to eliminate the liquid level vortex is reached. The number and width of baffles meeting the full baffle condition can be calculated by W * mb/D=0.4, where W is the baffle width, D is the tank diameter, and the unit is m, and mb is the number of baffle plates.
12. The function of stirring, commonly used forms of stirrers, and the characteristics of turbine and axial flow stirrers?
One is to generate a strong overall flow, evenly distributing the fluid throughout the container to achieve macroscopic uniformity; The second is to generate strong turbulence, which reduces the size of liquid, gas, and solid micro clusters. The two effects will be beneficial for mixing, heat and mass transfer, especially for the decisive role of oxygen dissolution.
The commonly used agitator forms include propeller, paddle, turbine, frame, and anchor. The agitator forms commonly used in fermentation tanks include turbine agitator and propeller agitator.
The characteristics of a turbine agitator: The liquid in the turbine agitator moves radially and tangentially inside the agitator, known as the radial type, which has the characteristics of low flow rate and high pressure head. In order to prevent bubbles from rising along the axis, a disc is installed in the center of the mixer. In a turbine agitator, the liquid leaves the agitator at a high velocity, causing intense vortex motion and significant shear forces near the outer edge of the blade. This can disperse the incoming bubbles more finely and improve the dissolved oxygen mass transfer coefficient.
The characteristics of an axial flow mixer include high flow rate, high uniformity of gas, solid, and liquid three-phase mixing, providing a favorable environment for fermentation; Low power consumption, energy-saving; Low flow shear force is beneficial for microbial growth; Strong gas control ability, conducive to oxygen dissolution, and improves fermentation level.
13. Briefly understand the principles of other forms of fermentation tanks.
Mechanical stirring self-priming fermentation tank
Air lift circulating fermentation tank
14. What are filtration and sedimentation? Three filtering mechanisms?
Filtration: It is a process of separating liquid-solid phases by using the differences in the density or particle size of liquid-solid particles under the action of driving forces (gravity, pressure, centrifugal force) to pass the suspension through a porous filter medium, intercept solid particles, and allow the filtrate to flow out through the filter medium. The presence or absence of filter media is the most distinct feature that distinguishes filtration from sedimentation separation.
Three filtering mechanisms:
(1) Filter cake filtration: Porous fabrics are commonly used as filter media, and their mesh size may not necessarily be smaller than the diameter of the intercepted particles. However, at the beginning of the filtration operation, some particles may enter the mesh of the filter media and cause bridging phenomenon. There are also a small number of particles that pass through the medium and mix with the filtrate at the beginning. However, as the filter residue gradually accumulates, a filter residue layer is formed on the filter media, which is called a filter cake. The continuously thickening filter cake is the truly effective filtering medium, and the liquid passing through the filter cake becomes a clear filtrate. Usually, the filtrate obtained at the beginning of the operation is turbid and needs to be returned for re filtration.
(2) Deep filtration: In deep filtration, solid particles do not form a filter cake, but rather deposit inside the thicker filter medium. At this point, the particle size is smaller than the pore size of the medium and can immediately enter the long and tortuous opening. Under the action of inertia and diffusion, solid particles entering the channel tend to adhere to the channel wall through static electricity and surface forces. Deep filtration is commonly used to purify suspensions with low solid content. The use of granular activated carbon for water pretreatment is based on this principle.
(3) Absolute filtration: The indicated pore size of the filter medium is smaller than the solid particles that are intercepted. Ultrafiltration in membrane separation equipment is a typical example of absolute filtration.
Sedimentation: It is the process of achieving liquid-solid separation by utilizing the density difference between liquid and solid and the velocity difference in a gravitational or centrifugal field. Therefore, the larger the density difference, the more favorable it is for separation; The larger the gravity field or centrifugal force field, the more favorable it is for separation. According to different driving forces, settlement can be divided into gravity settlement and centrifugal settlement.
15. What are the structures and characteristics of plate and frame filter presses, vacuum drum filter presses, and three legged centrifuges?
The plate and frame filter press consists of three parts: the frame, the clamping structure, and the filtering mechanism.
The characteristics of the plate and frame filter press are (1) simple structure, easy operation, less maintenance, convenient machine service life, and less equipment required. (2) Strong adaptability to materials. (3) The selection range of filtration area is wide (4), and the moisture content of the filter cake is low. (5) High solid-phase recovery rate and good filtrate clarity. (6) The detection, washing, and replacement of filter cloth are convenient (7), the filtering operation pressure is high (8), and the cost is low with minimal investment. (9) Intermittent operation, long auxiliary time, and high labor intensity.
Structure of vacuum drum filter: drum filter, washing solution storage tank, filtrate storage tank, mixing condenser, water tank
The advantage of vacuum drum filter is that it can achieve continuous operation for suction filtration, washing, slag unloading, regeneration and other operations, and can also be automatically controlled when necessary. The disadvantage is that there are many auxiliary devices with high power consumption, which are not suitable for finer or more viscous materials.
The advantages of a three legged centrifuge are: 1. Strong adaptability to materials. 2. Simple manual unloading structure, easy manufacturing and installation, convenient maintenance, low cost, and easy operation. 3. The elastic suspension support structure can reduce the vibration caused by uneven loads and ensure smooth operation of the machine. 4. The entire high-speed rotating structure is concentrated in a closed shell, which is easy to achieve sealed and explosion-proof
16. The structural principle of a tube centrifuge and a brief understanding of other forms of centrifuges.
Due to the small diameter and long length of the drum of the separator, which is shaped like a tube, it is called a tube centrifuge. Structure of tube centrifuge: (1) drum section; (2) Rack section; (3) Head section; (4) Pressure roller part; (5) Sliding bearing assembly part; (6) Driver part; (7) Liquid receiving tray section. Others include: spiral discharge centrifuge, biological separation centrifuge, disc centrifuge.

17. What are the mixing and separation equipment for segmented extraction equipment?
The mixing equipment includes mixing tanks, mixing pipes, jet extractors, and pumps.
Mixing tank: Generally, a mixing tank is a reaction tank with a stirring slurry, which usually uses a propeller stirrer with a speed of 400-1000r/min; If a turbine stirrer is used, the speed is about 300-600r/min. To avoid vortices, baffles should be installed on the tank wall. Mixing tanks are generally enclosed to reduce solvent evaporation. The average mixing residence time of liquids in a tank is about 1-2 minutes.
Mixing tube: a small volume and high-efficiency mixing device, especially suitable for situations where the viscosity and interfacial tension of two liquid phases are very low and easy to disperse.
Pump: When two liquids are relatively easy to mix, a centrifugal pump can be directly used to mix the liquid and solvent.
Separation equipment generally adopts tube centrifuge or disc centrifuge.
What are the three operating modes of ion exchange and the structural principles of the four ion exchange devices?
Ion exchange refers to a separation method based on the exchange between exchangeable ions on an ion exchanger and ions in a liquid phase. There are three methods of operation:
(1) Batch method (static adsorption method): Put the resin into a container containing the feed solution, gently stir it, and exchange it to reach equilibrium.
(2) Fixed bed method: The resin is placed in an ion exchange column or tank, and the feed liquid flows through the resin bed from top to bottom (positive adsorption) or from bottom to top (reverse adsorption), and the exchange is dynamic.
(3) Flowing bed method: Both the feed liquid and resin are in a flowing state, generally flowing in opposite directions (reverse direction), and the entire operation is completely continuous.
The structural principles of four types of ion exchange equipment: 1. General ion exchange tank 2. Anti adsorption ion exchange tank 3. Mixing exchange tank 4. Continuous countercurrent ion exchange equipment
What are evaporation and crystallization, the composition of evaporation equipment, the three processes of crystallization, and the classification of crystallization equipment?
Evaporation refers to the unit operation of heating a solution to vaporize a portion of the water or solvent in the solution and remove a solute that increases the concentration of the solute in the solution or concentrates the solution to saturation to precipitate the solute.
The evaporation equipment mainly consists of a vacuum system gas-liquid separator for evaporator condensation equipment.
Crystallization refers to an important operational unit for the precipitation of solid crystals from a homogeneous solution. Including three processes: 1. Forming a saturated solution; 2. Formation of crystal nuclei; 3 crystals Growth
Classification of Crystallization Equipment: 1. Cooling Crystallizer 2. Evaporative Crystallizer 3. Vacuum Crystallizer
20. What is dryness? What are the principles and characteristics of airflow drying, boiling drying, spray drying and freeze drying?
Drying often refers to the process of using thermal energy to vaporize moisture (or solvents) in materials, and the generated vapor is carried away by inert gases. Airflow drying refers to the operation of using high-speed hot air flow to dry materials during fluidized conveying. The characteristics are: 1. Good heat transfer effect, 2. Increased average temperature difference △ tm between gas and solid, 3. Simple equipment structure, easy manufacturing, small footprint, continuous operation, suitable for automatic control, 4. Wide applicability for drying various powder, granular, fragmented and muddy materials.
Boiling drying refers to the drying process in which wet material particles or powders placed on a sieve plate are in a boiling state using hot air flow.
The characteristics of boiling drying: The temperature in the boiling dryer is uniform, easy to control, and not prone to material overheating. Due to the controllable residence time of the material in the boiling dryer, the final moisture content of the material can be reduced to a very low level. In addition, the boiling dryer has good sealing performance, easy to ensure product purity, and a simple structure, making it widely used.
Spray drying refers to the process of drying highly dispersed solutions or suspensions with hot air. It is especially suitable for bioengineering products that cannot be crystallized into solid products.
Advantages of spray drying: (1) the drying process is fast; (2) the temperature of the material is low during the drying process; (3) the powder can be obtained directly from the liquid material, eliminating processes such as evaporative crystallization, separation and crushing, and can be operated under semi sterile conditions. (4) The quality of finished products can be controlled
Disadvantages of spray drying: (1) The volume drying intensity of spray drying is small, so its drying chamber is large; (2) spray drying consumes large energy, uses a large amount of drying medium, and is uneconomical in heat utilization; (3) The product will stick to the wall.
Freeze drying, also known as sublimation drying, is a drying process in which wet materials or solutions are frozen into a solid state at a lower temperature (-10~-50 ℃), and then the moisture in them is directly sublimated into a gaseous state under high vacuum, resulting in dehydration. Its main advantages are: (1) low operating temperature, and the dried material maintains its original chemical composition and physical properties (such as porous structure, colloidal properties, etc.); (2) Less heat consumption compared to other drying methods. The disadvantage is that the cost is high and it cannot be widely adopted. Used for drying antibiotics, vegetables, fruits, etc.
21. Working principle of air lift fermentation tank
An air lift fermentation tank is a device that uses compressed air sprayed from a nozzle to push the culture solution up along a guide tube (due to the low density of the liquid in the rich gas zone), circulating from the inside out or from the outside inside out to achieve mixing and mass transfer.
Supplementary section:
Drag force: It is the resistance experienced by particles when moving relative to a fluid, which is related to the fluid velocity, density, and diameter of solid particles (assuming that the particles are approximately spherical).
Sterilization process of culture medium tank: Steam must be introduced to all pipelines in contact with the culture medium (if the tank is equipped with a flushing mirror pipeline, steam must also be introduced to this pipeline), and steam must be discharged to all pipelines that are not in contact with the culture medium.
There are four criteria for determining the quality of sterilization of culture media in solid tanks: achieving sterility requirements after sterilization of the culture media; Less damage to nutritional components; After sterilization, the volume of the culture medium matches the volume of the material; Less foam.
Bioreactor: refers to a device for large-scale cultivation of microorganisms, animal cells, and plant cells to obtain their metabolites or organisms.
Fermentation tank: A reactor for large-scale suspension cultivation of microorganisms is commonly referred to as a fermentation tank.
The downstream processing of biotechnology: the process of separating and purifying relevant products from fermentation broth, reaction broth, or cell culture broth is collectively referred to as the downstream processing of biotechnology. This process involves both traditional chemical unit operations (such as liquid-solid separation, extraction, ion exchange, evaporation concentration, crystallization, drying) and developing biological separation technologies (such as chromatography, membrane separation, supercritical extraction, etc.).