Fermentation equipment: Fermenter renovation solution - Unlimited thinking to create more value

       Preface: It is well known that fermentation is a complex biochemical process of aseptic aeration (or anaerobic), which requires sterile air and pure submerged culture of medium, thus the design of fermentation tank is not only the design of single equipment but also involves the system engineering of medium sterilization, preparation of sterile air, control of fermentation process and process piping formulation.

       The renovation of fermentation tanks can be divided into the following aspects: replenishment, discharge, air, detection, dissolved oxygen capacity, tank properties, the purpose of the renovation includes the ease of operation of feeding and discharging, the safety of maintaining aseptic status, ensuring the safety of the tank, the improvement of system control, and most importantly, the improvement of dissolved oxygen capacity.

The catalog of the renovation projects provided in this paper is as follows:

1 Treatment of tank body passivation (anti-corrosion)

2 Pre-treatment of special materials (liquid dispensing system)

3 Replenishment piping inserted below liquid level (replenishment system)

4 Multi-head feeding device (replenishment system, can be disassembled and modified)

5 Increase the electrode socket (detection)

6 temporary change sampling port (sampling, electrode socket, can be disassembled and modified)

7 increase the bottom valve (discharge, cleaning)

8 the use of cyclone separator (escape liquid, defoaming)

9 Stirring paddle improvement (dissolved oxygen)

10 Air sterilization capacity improvement (miscellaneous bacteria, phage)

11 Heat and energy transfer system (defect improvement)

12 Stirring power improvement (DO)

13 Air distributor (DO)

1 Passivation treatment of the tank (anti-corrosion)

        The passivation treatment of the tank body is to improve the corrosion resistance of the tank body, especially for the microalgae fermentation process in the presence of more Cl- more fermentation system is necessary, the use of a longer period of time tank also need to be tank treatment, for details of this performance change in the program see the public "fermentation engineering" past history of the release of:

Fermentation equipment: stainless steel passivation process (passivation process) on the internal and external surfaces of the fermenter protection technology finishing

2 Special material pretreatment (liquid distribution system)

Viscous materials into the tank can be used homogenizer or homogenization pump, glucose is best to increase the sugar tank single elimination.

3 In-tank replenishment piping (replenishment system)

     For volatile flow addition items, if continuous low speed flow addition is used it is best to modify the flow addition pipeline to insert below the liquid level to prevent air from taking away causing material loss and process instability. The effect is shown in the following figure:

4、Multi-head inlet device (refill system, can be disassembled and modified)

       For complex replenishment process, sometimes it is necessary to temporarily add replenishment inlet on the tank, if it is a small trial, it can be modified to use multi-fast joint method, and after the process is fixed, the fast joint can be added by drilling holes.

(Here thanks to the fermentation engineering fans for the picture)

5、Add electrode socket (detection)

       There are three electrodes connected to the diagram: pH, DO, and T, which are sufficient for conventional fermentation, but for some special types of fermentation, the electrode socket is less, such as methanol-induced fermentation, you may need to increase the methanol membrane permeator, and then methanol charge pump online coupling control, you only need to set the concentration of the point can be, no need to sample to detect the concentration of methanol and then intermittent replenishment or continuous flow plus speed regulation, so large production scale can consider improving the tank, increasing the electrode socket to improve production efficiency.

6、temporary change of sampling port (sampling, electrode socket, can be disassembled and modified)

       For small tanks without bottom valve and intermediate sampling port, when long time fermentation, sampling difficulties may occur in the middle and late stages, if the sampling of the unused electrode socket is modified according to the following diagram, this problem can be solved.

(Thanks to the fermentation project fans for the picture here)

7 increase the bottom valve (discharge, cleaning)

       Some tanks have a defective design, as shown in the figure below, there is no bottom valve, drainage and discharge rely on pressurized air to beat out, this equipment wash tank water discharge is not clean, put the material is not complete, the transformation to increase the bottom valve is very necessary.

(Here thanks to the fermentation project fans to provide pictures)

       The above picture of a small tank without bottom valve, only a jacketed circulation tube underneath, the tank stinks, precisely because how to wash can not be clean, material residue is very serious.

8 cyclone separator use (escape liquid, defoaming)

       The role of cyclone is to eliminate foam and limit escaping liquid, there will be no toxic effect of chemical defoamer on the bacterium, and the efficiency is more efficient than physical defoaming solution, see the public number "Fermentation Engineering" past history release:

Fermentation equipment: escaping of fermentation broth (escaping of fermentation broth) control of cyclone separator

9 Stirring paddle improvement (dissolved oxygen)

        The stirrer is installed in the fermenter to firstly disperse the air bubbles to obtain the highest possible mass transfer coefficient KLa. In addition, the stirred fermentation broth is circulated to increase the average residence time of the bubbles and to distribute them evenly throughout the system to prevent their aggregation. Earlier in the mechanical stirring fermenter is usually equipped with several radial disc turbine stirrers, but it is easy to make the stirred medium stratified and formed several zones, thus forming an oxygen partial pressure gradient between the lower and upper part of the tank, resulting in the difference of KLa values between the upper and lower part of the tank. Recently, the stirring system of fermenter mostly adopts a turbine stirrer installed at the bottom of the tank to disperse the air, and then a set of axial stirrer installed on top of it, which is used to circulate the culture medium, distribute the bubbles evenly, enhance the heat transfer and eliminate the difference of oxygen gradient between the upper and lower parts of the tank.

Mixing blade forms:

(1) Open turbine mixing blade with disc --- high turbulence, radial flow.

(2) Pitchedbiade turbine (p - 4) --- 45° four blades, axial flow.

(3) Reverse tilt (Reversingpitch) mixing blade --- two up, two down, radial flow.

(4) High efficiency axial flow mixing blade --- A310, axial flow.

(5) Mixed-flow stirring impeller --- A315, axial flow, a small amount of radial flow.

(6) Concaveblade radial --- CD --- 6, radial flow.

The specific form is published in the past history of public number "Fermentation Engineering":

Fermentation equipment: selection criteria of stirrers and the effect of different leaf shapes of stirrers on fermentation mash

10 Improvement of air sterilization capacity (miscellaneous bacteria, phages)

Phages are extremely small but also easily heat denatured, they can easily enter the tank through the air system, if you do bacterial fermentation, it is recommended to set up a heating sterilization link in the fermentation air system

       A more economical approach is to use the air compressor compression heat generation for heat preservation sterilization, the import temperature 21-22 ℃, the export temperature 187-189 ℃, pressure 0.7 Mpa.

11 Heat transfer system (defective improvement)

        Above 2 square welding head, 2 square flange head, below 5 square jacket heating, above 5 square serpentine tube heating, microbial fermentation system for heat control is very strict.

       There was a veterinary fermentation enterprise in Gansu, surprisingly, there is no heating water intake device in the expansion tank, after the transfer of the tank intends to rely on microbial heat production to maintain the energy of the system, but once in winter (Gansu winter is colder), this program will not work, so the transformation of the energy system to strengthen the focus of each fermentation engineer should also consider.

12 Stirring power improvement (DO)

       This item involves the choice of stirring motor, the speed of the motor is not the speed of the stirring shaft, there is a reducer between the motor and the stirring shaft, involving the speed ratio conversion, the motor power is too small will affect the dissolved oxygen capacity, according to the microbial characteristics in the hands of the appropriate change to a higher speed or speed ratio of the motor is a good choice.

(Thanks to a fan of fermentation engineering for the picture here)

       The graph shows the electrode speed ratio 1.48, that is, the maximum speed of electrode 1435 r/min to stirring shaft speed 970 r/min

       In addition, the belt reducer has a large size, relatively low transmission efficiency, and the speed ratio cannot be strictly controlled. Therefore, in recent years, some engineering designers use vertical gear reducer

13 Air distributor (DO)

       Small tank diameter to height ratio is not as high as the large tank, ventilation into the tank soon after the movement to the liquid surface above, in order to dissolve oxygen can increase the air distributor to the end of the intake pipe (some small tank manufacturers do not do the distributor), need to pay attention to the nature of the fermentation solution, too viscous may block the small hole of the air distributor.