The stirrer is one of the key components of the reactor. Choosing the appropriate stirrer according to the physical properties, capacity and stirring purpose of different media in the kettle can play a great role in promoting the speed of chemical reaction and improving the production efficiency.

　　Mastering the classification and application of stirrer can help to choose the right stirrer and achieve better reaction effect!

　　I. Application of reactor

　　Reactors are widely used in petroleum, chemical, rubber, pesticide, dyestuff, medicine, food, and are used to complete the process of vulcanization, nitrification, hydrogenation, hydrocarbonization, polymerization, condensation and other pressure vessels.

　　Composition of reaction kettle

　　Reaction kettle is composed of kettle body, cover, jacket, stirrer, transmission device, shaft sealing device, support, etc.

　　1. Shell of reaction kettle

　　The shell is composed of a round cylinder, upper cover and lower head. There are two ways to connect the upper cover with the barrel, one is to weld the cover and barrel directly to form a whole; the other form is to consider the convenience of disassembly, available flange coupling. The upper cover is opened with manhole, hand hole and process receiver.

　　2. Stirring device of reaction kettle

　　In the reaction kettle, in order to speed up the reaction speed, enhance the mixing and strengthen the mass transfer or heat transfer effect, the reactor is generally equipped with stirring device. It consists of stirrer and stirring shaft, which is connected with the transmission device by coupling.

　　3. Sealing device of reactor

　　The sealing device used in the reactor is the dynamic sealing structure, there are mainly two kinds of packing seal and mechanical seal.

　　C. Classification and selection

　　1. The role of reactor stirrer

　　Mixing and homogenizing materials, strengthening heat and mass transfer, including homogeneous liquid mixing; liquid-liquid dispersion; gas-liquid dispersion; solid-liquid dispersion; crystallization; solid dissolution; strengthening heat transfer, etc.

　　2. Reactor stirring principle

　　The main component of the stirrer is the impeller, which moves with the rotating shaft to apply mechanical energy to the liquid and induce the liquid to move.

　　When the stirrer rotates, the mechanical energy is transferred to the fluid, forming a highly turbulent and fully mixed area near the stirrer, and generating a high-speed jet to push the liquid to circulate in the stirred vessel.

　　Four, paddle stirrer

　　It is composed of paddle, key, shaft ring and vertical shaft. The paddle is generally made of flat steel or stainless steel or non-ferrous metal. The rotational speed of paddle stirrer is low, generally 20~80r/min.

　　The diameter of the paddle stirrer is Di/3~2/3 of the inner diameter of the reactor. The paddle should not be too long, and two or more paddles are used when the diameter of the reactor is large.

　　Main applications: Paddle stirrer is suitable for liquid materials with high fluidity and low viscosity, and also for fibrous and crystalline dissolved liquids, and several rows of paddles can be installed on the shaft when the material layer is deep. Folded blade type has less power consumption and lower operating cost than the flat blade type, so the folded blade paddle is used more often.

　　Paddle stirrer can not be used in gas-liquid dispersion operation for the purpose of maintaining gas and fine-tuning.

　　V. Propulsion type stirrer

　　Propeller stirrer can circulate the material in the reactor when stirring, and the effect is mainly volume circulation, with less shearing effect and good up and down tumbling effect. When a larger flow rate is needed, the reactor is equipped with a flow guide cylinder.

　　The standard propulsion stirrer has three blades with a pitch equal to the paddle diameter d. The diameter of the propulsion stirrer is about 1/4 to 1/3 of the inner diameter Di of the reactor, 300 to 600r/min. The material of the stirrer is often cast iron and cast steel.

　　Sixth, turbine stirrer

　　The speed of turbine stirrer is larger, 300~600r/min. The straight and curved blade turbine stirrer mainly produces radial flow, and the folded blade turbine stirrer mainly produces axial flow.

　　The main advantage of turbine stirrer is that when the energy consumption is not much, the stirring efficiency is high and the stirring produces very strong radial flow. Therefore, it is suitable for emulsions, suspensions, etc.

　　VII. Anchor stirrer

　　It is suitable for mixing fluid with viscosity below 100Pa-s. When the fluid viscosity is 10~100Pa-s, a horizontal paddle can be added in the middle of the anchor paddle, which is a frame stirrer, to increase the mixing in the middle of the container.