Domestic science and technology and production technology are changing with each passing day, and the sealing requirements of the biopharmaceutical industry have become more and more stringent. The coordination of the reaction tank and the mixing device is an important part of the entire production process, so the CGMP (Dynamic Drug Production Management Specifications) requirements for the online cleaning (CIP) and online bacteria (SIP) of reaction devices are particularly strict. In this context, the application prospects of magnetic stirring technology have been widely optimistic about technicians in the industry.
Magnetic stirring device structure
Balun magnetic stirrer
The magnetic stirring device is mainly composed of a driving motor, an inner magnetic sleeve connected to the motor, an isolation sleeve connected to the tank, an outer magnetic sleeve integrated with or connected to the stirring blades, and bearings. The device relies on magnetic transmission, that is, based on the principle of magnetic mechanics, and uses the principle of mutual repulsion and attraction between magnet materials to form an effect and transmit the torque and speed of the drive motor to the stirring blades in a non-contact manner, thereby driving the inside materials of stirred tank bioreactor are mixed to achieve the purpose of full reaction.
According to the structure of the transmission device, the magnetic stirring device can be divided into: cylindrical magnetic stirring device and disc magnetic stirring device; according to the use occasion, it can be divided into: experimental type and production type magnetic stirring device; according to the installation method, it can be divided into: top magnetic stirring device and bottom magnetic stirring device; according to the driving mode, it can be divided into: internal magnetic drive stirring device and external magnetic drive stirring device.
Key points in structural design of magnetic stirring device
Isolation sleeve
The isolation sleeve of the stirring device is shown in the figure below. It is between the driven magnetic rotor and the active magnetic rotor. During the rotation of the magnetic rotor, the isolation sleeve is in an alternating magnetic field. According to Faraday’s principle, the changing magnetic field will generate an electric field, thereby forming a current. This creates vortices. Eddy currents will weaken the magnetic field relative to the reaction work, resulting in a decrease in the transmitted torque. Additional losses will appear in the form of heat energy, and the released heat energy may have an impact on temperature-sensitive materials.
rolling bearing
Through magnetic transmission, the dependence on packing seals (currently not applicable in the biopharmaceutical field) and mechanical seals in the mechanical transmission process is directly eliminated at the material level, effectively solving the problems of dynamic seal leakage and incomplete space isolation.
For positioning bearings, Bra Precision Machinery mainly uses ceramic bearings with extremely strong corrosion resistance and wear resistance (as shown in the figure below) to achieve the positioning of the master and slave rotors. At the same time, the bearing installation space is designed in conjunction with ASME-BPE cleaning requirements. The rotating flow channel relies on the flow of materials to form a lubricating film between the bearings to achieve the purpose of lubricating the bearings.
Mixing paddle
The core component in the mixer that achieves mixing, mass transfer, and heat transfer is the paddle. Its function is to provide a suitable energy flow field to the materials in the reaction tank through rotation to achieve mixing and contact purposes. At present, according to the mixing process, the basic forms of paddles can be mainly divided into paddle type, turbine type, propeller type, anchor type, frame type, ribbon type and rake type, etc., as shown below (the picture shows one of the structures – turbine structure )
Summary and Outlook
The significance of mechanical structure design is to solve problems encountered in production and use. How to combine and innovate classic mechanical structures based on process characteristics is the primary issue facing manufacturing companies that focus on application. In order to effectively solve the hygiene problem in the field of biopharmaceuticals, reasonable processing technology changes can be adopted to reduce or eliminate areas where potential materials may exist. At the same time, design verification, performance verification, operation verification and riboflavin testing can be performed before delivery. Regarding the traceability issue that the biopharmaceutical industry is concerned about, on the one hand, equipment manufacturing companies need to control quality from the source of materials and pay attention to the combination of documents and material consistency; on the other hand, they need to further integrate the mixing device and the reaction tank in terms of control. Integration, through intelligent penetration testing, realizes the connection between mixing and material reaction conditions, and further introduces an audit trail mode to provide necessary data support for traceability.
Balun magnetic stirring system
About Bailun
Balun has extensive experience in manufacturing various types of reactors and pressure vessels. We have a team of experts in the fields of biological reactions, fermentation processes, machinery manufacturing, and automation control. Our scientific research and technology levels are always at the leading level in China and among the best in the world, providing you with a comfortable, assured, and secure product experience.
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