JPS5823073B2 - How to adjust dissolved oxygen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for facilitating the cultivation of microorganisms by converging the dissolved oxygen in a microorganism culture solution or sludge to the required amount.

Adjusting the amount of dissolved oxygen in a solution is considered to be an essential element in increasing the yield of microorganisms such as yeast bacteria, but this adjustment has traditionally been done manually, relying on intuition and skill. Therefore, not only was there a great deal of variation, but also the cultivation required continuous operation for 24 to 72 hours, which required considerable labor, and there was a desire to automate this process.

On the other hand, in recent years, the technology disclosed in Japanese Patent Publication No. 45-18273 has been published for automated culture of microorganisms, but this technology limits the amount of dissolved oxygen in the culture solution to within a set upper and lower limit. If the measured amount of dissolved oxygen exceeds the upper or lower limits, increase or decrease stirring or aeration to supply the appropriate amount of oxygen, and if the measured value is within the above range (tolerable range), stir or aerate. This design prevents the amount of aeration from increasing or decreasing, which makes it possible to automatically operate the culture.

However, in the above technique, two positions, an upper limit and a lower limit, are set, and when the amount of dissolved oxygen is within an allowable range, the previous state is maintained in both stirring and aeration.

However, if the measured value deviates from the permissible range, the oxygen consumption will change several times or more in a short period of time, so it will take a considerable amount of time to bring the value back within the permissible range. This has a negative effect on the microorganisms that are exposed to the microorganisms, and there is a possibility that culturing of microorganisms that are particularly sensitive to oxygen levels may become impossible.

This invention was made to eliminate the above-mentioned drawbacks, and provides a method that not only automatically adjusts the amount of dissolved oxygen but also allows the amount of dissolved oxygen to be constantly adjusted to be close to a predetermined set value. This will be explained in detail below.

FIG. 1 is a schematic diagram showing the method of this invention. Reference numeral 1 is a jar for culturing microorganisms, and a tank 1a is equipped with a stirrer 2 and an electrode 3 for measuring the amount of dissolved oxygen in the solution. ,
The starter 1b includes a stirring motor 4 and a generator 5 that transmits the rotational speed of the stirrer 2 connected to the stirring motor 4 in a sequence to be described later.

The stirring bar 2 is used to stir the solution in the tank 1a by transmitting the rotational driving force of the stirring motor 4 by an appropriate means such as a magnet, and the stirring of the starter 1b removes oxygen from the air into the solution. It is designed to dissolve in

The measurement electrode 3 is connected to a recorder 6 and a time proportional controller 7, and the measured value of the electrode 3 is transmitted to both the recorder 6 and the time proportional controller 7, and the recorder 6 transmits the measured value to the recorder 6 and the time proportional controller 7. Correlating the measured value with the rotation speed of the starter 1b and recording it on a graph, sensing the measured value with the time proportional controller 7 and simultaneously calculating the deviation between the measured value and a preset setting value, The speed increase or deceleration operation time ratio of the stirring motor 4 is determined according to this deviation, and this is converted into an electrical signal and transmitted to the motor 4 via the sequence 8.
It is what drives the.

The above sequence 8 converts the electric signal from the time proportional controller 7 into an amount of speed increase or deceleration using a built-in potentiometer and a reversible motor that drives this potentiometer, and transmits this to the stirring motor 4. , receives a signal from the generator 5 and uses it as a recording signal to be transmitted to the recorder 6.

In the present invention configured as described above, first, a required amount of dissolved oxygen is set in advance according to the type of microorganism to be cultured and the amount of culture, and is stored in the time proportional controller 7.

Next, the amount of dissolved oxygen in the solution is measured by the electrode 3 installed in the tank 1a, and this is transmitted to the recorder 6 for recording, and is also transmitted to the time proportional controller 7.

The time proportional controller 7 calculates the deviation between the measured value and the set value as described above, determines the operating time ratio for speeding up or decelerating the stirring motor 4, and transmits this to the stirring motor 4 through the sequence 8. 4 to make the deviation zero.
It rotates while speeding up or slowing down, creating a swirling flow that dissolves the required amount of oxygen in the air.

At the same time, by recording the rotational speed of the stark 1b with a recorder 6, a correlation graph of measured values, set values, and rotational speed as shown in FIG. 2 is obtained.

Therefore, for example, even if the deviation of the measured value immediately after driving is large, the deviation repeats plus and minus and gradually approaches the set value, and after a certain period of time, it almost converges to the set value and the fluctuation of the measured value disappears, and the microorganism A good environment for culture can be obtained.

In this case, the amount of oxygen required varies depending on the type and amount of microorganisms to be cultured, and the capacity of the stirring motor may be selected accordingly.

As detailed above, in the case of the method of this invention,
It is possible to completely automate the adjustment of the amount of dissolved oxygen, which reduces the number of personnel involved, does not require any skill, and is not only easy to work with, but also allows the amount of dissolved oxygen to gradually converge to the set value. As a result, fluctuations in measured values are almost eliminated after a certain period of time, and a very good culture environment can be obtained, resulting in excellent effects, and according to the present invention, it is cheaper and simpler than the PID control method. On
-Higher quality control than the off control method is possible.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram according to the present invention, and FIG. 2 is a correlation graph obtained according to the present invention. 1...Jar, 1b...Stark, 2
... Stirrer, 3... Electrode, 4...
... Stirring motor, 5... Generator, 6.
...Recorder, 7...Time proportional controller,
8...Sequence.

Claims (1)

[Claims] 1 By measuring the amount of dissolved oxygen in the solution, it is possible to adjust the speed-up or deceleration operating time ratio of the stirring motor according to the deviation between the measured value and the set value so as to reduce the deviation to zero. Characteristic method for adjusting dissolved oxygen.