The stirrer is one of the indispensable instruments for organic chemistry experiments. It can make the reaction mixture more uniform and the temperature of the reaction system is more uniform, which is favorable for the chemical reaction, especially the heterogeneous reaction. Widely used in chemical, food, dyes, cosmetics, pharmaceutical industry. Since its development, the application of stirrers has become increasingly diversified and specialized, and it has been continuously improved.
The type, size, and speed of the stirrer affect the distribution of the stirring power between the overall flow and the turbulent pulsation. In general, the power distribution of a turbine-type agitator is favorable for turbulent pulsation, and the propeller agitator is advantageous for overall flow. For the same type of agitator, under the condition of the same power consumption, the large-diameter, low-speed stirrer mainly consumes the power in the overall flow, which is favorable for macro-mixing. Small-diameter, high-speed stirrers, whose power is mainly consumed by turbulent pulsations, are conducive to microscopic mixing. There are three methods of stirring: manual mixing, magnetic stirring, and mechanical stirring. Manual stirring is generally performed by means of a glass rod, magnetic stirring using magnetic force, and mechanical stirring using a mechanical stirrer.
The mechanical stirrer mainly includes three parts: a motor, a stirring bar and a stirring and sealing device. The motor is the power part, fixed on the bracket, and its speed is adjusted by the governor. The stirring rod is connected with the motor. When the power is turned on, the motor drives the stirring rod to rotate, and the stirring and sealing device is a device connecting the stirring rod and the reactor, which can make the reaction proceed in the sealing system. The efficiency of the agitation depends to a great extent on the structure of the stir bar. The old stir bar introduced is made of coarse glass rods. According to the size, shape of the reactor, the size of the bottle mouth and the reaction conditions required, choose a more appropriate stir bar.
The magnetic stirrer uses the same principle of repulsion of the magnetic field and attracts the opposite sex. The magnetic field is used to push the magnetic stirrer placed in the container to run in a circle, so as to achieve the purpose of stirring the liquid, especially when the reaction amount is less or in response. It is the case under the confined condition. The magnetic stirrer is more convenient to use, can heat and control the sample temperature according to the specific experimental requirements, maintain the temperature conditions required for the experimental conditions, and ensure that the liquid mixture meets the experimental requirements. However, the disadvantage is that for some viscous liquids or reactions in which a large amount of solids participate or generate, the magnetic stirrer cannot be used smoothly. At this time, a mechanical stirrer should be used as the stirring power.
Magnetic stirrers are usually used in food, biopharmaceuticals and other fields. As biopharmaceuticals place higher demands on the sterility and risk control of shaft seals for mixers, industrial magnetic stirrers have emerged in Sweden in the 1980s. The magnetic stirrer becomes the mainstream in the market, and continues to develop in the direction of simplicity, high torque, large shear force or very low shear force, safe bearing material, easy on-line cleaning, and on-line sterilization. For example, a magnetic stirrer dedicated to a bioreactor, a high-shear homogenizer, and a magnetic stirrer are used. Is it possible to prove that the stirrer can be cleaned online and sterilized on-line, bearing material safety, etc., become the gold standard for selection of biopharmaceutical mixers.
In addition, the bench-top magnetic stirrer uses the characteristic of the same repulsion of the magnetic substance, and the rotation of the magnetic stirring rod is promoted by constantly changing the polarities of both ends of the base; the disadvantage is that the energy conversion efficiency is low, and it is only suitable for the stirring of a small volume of liquid. Although bench-top magnetic stirrers and magnetic bars have been widely used, they are currently limited to R&D and small-scale levels. As the level of scientific research in the country has been greatly improved, the application of magnetic stirrers will gradually expand and become the leading instrument in the industry. .
The type, size, and speed of the stirrer affect the distribution of the stirring power between the overall flow and the turbulent pulsation. In general, the power distribution of a turbine-type agitator is favorable for turbulent pulsation, and the propeller agitator is advantageous for overall flow. For the same type of agitator, under the condition of the same power consumption, the large-diameter, low-speed stirrer mainly consumes the power in the overall flow, which is favorable for macro-mixing. Small-diameter, high-speed stirrers, whose power is mainly consumed by turbulent pulsations, are conducive to microscopic mixing. There are three methods of stirring: manual mixing, magnetic stirring, and mechanical stirring. Manual stirring is generally performed by means of a glass rod, magnetic stirring using magnetic force, and mechanical stirring using a mechanical stirrer.
The mechanical stirrer mainly includes three parts: a motor, a stirring bar and a stirring and sealing device. The motor is the power part, fixed on the bracket, and its speed is adjusted by the governor. The stirring rod is connected with the motor. When the power is turned on, the motor drives the stirring rod to rotate, and the stirring and sealing device is a device connecting the stirring rod and the reactor, which can make the reaction proceed in the sealing system. The efficiency of the agitation depends to a great extent on the structure of the stir bar. The old stir bar introduced is made of coarse glass rods. According to the size, shape of the reactor, the size of the bottle mouth and the reaction conditions required, choose a more appropriate stir bar.
The magnetic stirrer uses the same principle of repulsion of the magnetic field and attracts the opposite sex. The magnetic field is used to push the magnetic stirrer placed in the container to run in a circle, so as to achieve the purpose of stirring the liquid, especially when the reaction amount is less or in response. It is the case under the confined condition. The magnetic stirrer is more convenient to use, can heat and control the sample temperature according to the specific experimental requirements, maintain the temperature conditions required for the experimental conditions, and ensure that the liquid mixture meets the experimental requirements. However, the disadvantage is that for some viscous liquids or reactions in which a large amount of solids participate or generate, the magnetic stirrer cannot be used smoothly. At this time, a mechanical stirrer should be used as the stirring power.
Magnetic stirrers are usually used in food, biopharmaceuticals and other fields. As biopharmaceuticals place higher demands on the sterility and risk control of shaft seals for mixers, industrial magnetic stirrers have emerged in Sweden in the 1980s. The magnetic stirrer becomes the mainstream in the market, and continues to develop in the direction of simplicity, high torque, large shear force or very low shear force, safe bearing material, easy on-line cleaning, and on-line sterilization. For example, a magnetic stirrer dedicated to a bioreactor, a high-shear homogenizer, and a magnetic stirrer are used. Is it possible to prove that the stirrer can be cleaned online and sterilized on-line, bearing material safety, etc., become the gold standard for selection of biopharmaceutical mixers.
In addition, the bench-top magnetic stirrer uses the characteristic of the same repulsion of the magnetic substance, and the rotation of the magnetic stirring rod is promoted by constantly changing the polarities of both ends of the base; the disadvantage is that the energy conversion efficiency is low, and it is only suitable for the stirring of a small volume of liquid. Although bench-top magnetic stirrers and magnetic bars have been widely used, they are currently limited to R&D and small-scale levels. As the level of scientific research in the country has been greatly improved, the application of magnetic stirrers will gradually expand and become the leading instrument in the industry. .
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