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Simple and easy to understand: classification, adv (14th Dec 22 at 7:33am UTC)Quote Reply
Original Title: Simple and Easy to Understand: Classification, Advantages and Disadvantages and Selection of Various Reactor Agitators The agitator is one of the key components of the reactor. According to the physical properties, capacity and stirring purpose of different media in the reactor, the selection of the corresponding agitator can play a great role in promoting the chemical reaction speed and improving the production efficiency. Mastering the classification and application of the agitator is helpful to choose the right agitator to achieve better reaction effect. Learn from Xiao Qi! Application of reaction kettle Reactor is a pressure vessel widely used in petroleum, chemical industry, rubber, pesticides, dyes, medicine and food to complete the process of vulcanization, nitration, hydrogenation, alkylation, polymerization and condensation. The composition of the reactor Expand the full text The reaction kettle consists of a kettle body, a kettle cover, a jacket, a stirrer, a transmission device, a shaft sealing device, a support and the like. 1 Shell of reaction kettle The shell consists of a circular cylinder, an upper cover and a lower end socket. There are two ways to connect the upper cover and the cylinder: one is to weld the cover and the cylinder directly to form a whole; the other is to consider the convenience of disassembly ? Flange connection is available. The upper cover is provided with a manhole, a hand hole, a process connecting pipe and the like. 2 Stirring device for reaction kettle In the reaction kettle, in order to speed up the reaction, enhance mixing and strengthen the mass transfer or heat transfer effect, the reaction kettle is generally equipped with a stirring device. It consists of a stirrer and a stirring shaft, which are connected with a transmission device by a coupling. 3 Aling device for reaction kettle The sealing device used in the reaction kettle is a dynamic seal structure, mainly including packing seal and mechanical seal. Classification and Selection of Agitators for Reactor Function of reactor agitator Uniformly mixing materials, enhancing heat transfer and mass transfer, including homogeneous liquid mixing, liquid-liquid dispersion, gas-liquid dispersion, solid-liquid dispersion, crystallization, solid dissolution, heat transfer enhancement, etc. Agitation principle of reaction kettle The agitator is the main component to realize the mixing operation. Its main component is the impeller, jacketed glass reactor ,winterization filtration, which applies mechanical energy to the liquid with the movement of the rotating shaft and promotes the movement of the liquid. When the stirrer rotates, the mechanical energy is transferred to the fluid to form a highly turbulent fully mixed zone near the stirrer, and a high-speed jet is generated to push the liquid to circulate in the stirring container. Influencing factors of agitation in reactor The way in which the liquid circulates within the scope of the equipment is called the "flow model" of the liquid, or "flow pattern" for short. Flow pattern is closely related to stirring effect and stirring power. The flow pattern depends on the form of the agitator, the geometry of the agitator vessel and internals, as well as fluid properties, agitator speed, and other factors. Axial flow The flow direction of that fluid is parallel to the stir shaft, and the fluid is pushed by the blade to flow downward and then turn upward when meeting the bottom surface of the container to form an up-and-down circulating flow. Radial flow The flow direction of that fluid is perpendicular to the stir shaft, the fluid flows along the radial direction, the fluid is divide into two streams of fluid when touching the wall surface of the container, and the two stream of fluid respectively flow upwards and downwards and then return to the blade end without passing through the blade to form upper and lower circulating flows. Tangential flow In the container without baffle, the fluid rotates around the axis, and when the flow rate is high, the surface of the liquid will form a vortex, and the flow rate of the fluid from the periphery of the blade to the blade area is very small, so the mixing effect is very poor. The above three flow patterns usually exist simultaneously; Axial flow and radial flow play a major role in mixing; Tangential flow should be suppressed — use of baffles can reduce tangential flow and enhance axial and radial flow. Classification and Application of Reactor Agitator Paddle type, pusher type, turbine type and anchor type agitators are most widely used in stirring reaction equipment, accounting for about 75-80% of the total number of agitators according to statistics. 1 Paddle agitator Consists of a blade, a key, a shaft ring and a vertical shaft. The blade is generally made of flat steel or stainless steel or non-ferrous metal. The rotating speed of paddle agitator is low, generally 20 ~ 80 R/min. The diameter of the paddle agitator shall be Di/3 ~ 2/3 of the inner diameter of the reaction kettle. The paddle shall not be too long. When the diameter of the reaction kettle is very large, two or more paddles shall be used. Main applications: The paddle agitator is suitable for liquid materials with high fluidity and low viscosity, as well as fibrous and crystalline solutions. When the material layer is very deep, several rows of paddles can be installed on the shaft.
The folding blade type has less power consumption and lower operating cost than the straight blade type, so the folding blade propeller is used more. The paddle type agitator cannot be used in the gas-liquid dispersion operation for the purpose of keeping the gas and for the purpose of fining. The rotating speed of the paddle agitator is generally 20 ~ 100 R/min, and the common parameters are shown in the following table: 2 Propeller agitator The propeller-type stirrer can make the materials circulate in the reaction kettle during stirring, and the function is mainly volume circulation, the shearing function is small, and the up and down tumbling effect is good. When a larger flow rate is required, the reaction kettle is internally provided with a guide cylinder. The standard propeller agitator has three blades with a pitch equal to the diameter d of the impeller. The diameter of the propeller agitator is about 1/4 ~ 1/3 of the inner diameter Di of the reactor, 300 ~ 600r/min. The agitator is usually made of cast iron and cast steel. Features of the pusher agitator: An axial flow agitator; The circulation quantity is large, and the stirring power is small; Imple structure and convenient manufacture; Commonly used in low viscosity fluids. 3 Turbine agitator Turbine agitator speed is high, 300 ~ 600r/min. Turbine agitators with straight and curved blades mainly produce radial flow, while turbine agitators with folded blades mainly produce axial flow. The main advantage of the turbine agitator is that when the energy consumption is not large, the stirring efficiency is high, and the stirring produces a strong radial flow. It is therefore suitable for use in emulsions, suspensions, etc. 4 Anchor agitator It is suitable for mixing the fluid with viscosity below 100Pa · s. When the fluid viscosity is between 10 and 100Pa · s,rotovap distillation, a cross blade can be added in the middle of the anchor paddle, which is a frame agitator, to increase the mixing in the middle of the container. Features of anchor agitator: Imple structure and convenient manufacture; It is suitable for materials with high viscosity and large handling capacity; A large surface heat transfer coefficient is easily obtained; It can reduce the generation of "wall hanging". Selection of Agitator for Reactor I. Type selection according to the purpose of mixing II. Type selection according to agitator type and applicable conditions Direct source of the article: Yaoyan Zongheng Public Number Virtue is all-powerful R & D Flagship of Wanquan China Known as the engine of China's pharmaceutical industry Honored for 15 years New Drug R & D and New Drug Approval Rank Top Apply for thousands of patents Return to Sohu to see more Responsible Editor:.
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