Wx-4000 reaction kettle mixer supplied by the manufacturer
The reactor agitator is one of the key components of the reactor. Selecting the appropriate agitator according to the physical properties, capacity and mixing purpose of different media in the reactor can play a great role in promoting the chemical reaction speed and improving the production efficiency. Mastering the classification and application of agitators will help to select the right agitator and achieve better reaction effect. Learn from the mechanics of dry people!
Reactor agitator
Application of reactor agitator
Reactor is a pressure vessel widely used in petroleum, chemical industry, rubber, pesticide, dye, medicine and food to complete the process of vulcanization, nitration, hydrogenation, alkylation, polymerization and condensation.
Composition of reactor agitator
The reaction kettle is composed of kettle body, kettle cover, jacket, agitator, transmission device, shaft seal device, support, etc.
Reactor agitator
1. composition of reaction kettle
The reaction kettle is composed of a circular cylinder, an upper cover and a lower head. There are two methods for connecting the upper cover and the cylinder. One is that the cover and the cylinder are directly welded to form a whole; Another form is to consider convenient disassembly and flange connection. The upper cover is provided with manhole, handhole, process nozzle, etc.
2. mixing device of reaction kettle
In order to speed up the reaction speed, strengthen mixing and enhance the mass transfer or heat transfer effect, the reaction kettle is generally equipped with a stirring device. The utility model is composed of a stirrer and a stirring shaft, which are connected with a transmission device by a coupling.
Reactor agitator
3. sealing device of reaction kettle
The sealing device used in the reactor is a dynamic sealing structure, mainly including packing seal and mechanical seal.
Classification and type selection of agitator for reaction kettle
Function of reactor agitator
Make the materials mix evenly, strengthen heat and mass transfer, including homogeneous liquid mixing; Liquid liquid dispersion; Gas liquid dispersion; Solid liquid dispersion; crystal; Solid dissolution; Strengthen heat transfer, etc.
Reactor agitator
Stirring principle of reaction kettle
The agitator is the main component to realize the mixing operation. Its main component is the impeller, which applies mechanical energy to the liquid with the movement of the rotating shaft and promotes the movement of the liquid.
When the agitator rotates, the mechanical energy is transferred to the fluid, forming a fully mixed zone with high turbulence near the agitator, and generating a high-speed jet to drive the liquid to circulate in the stirred vessel.
Influencing factors of reactor stirring
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.
The flow pattern is closely related to the mixing effect and mixing power. The flow pattern depends on the form of the agitator, the geometric characteristics of the mixing vessel and internals, as well as the fluid properties, the speed of the agitator and other factors.
Reactor agitator
Axial flow
The fluid flow direction is parallel to the mixing shaft, and the fluid is pushed by the paddle to make the fluid flow downward, and then turn up when it meets the bottom of the container, forming an up-down circulating flow.
Radial flow
The flow direction of the fluid is perpendicular to the mixing shaft and flows along the radial direction. When it touches the wall of the vessel, it is divided into two streams of fluid, which flow upward and downward respectively, and then return to the blade end without passing through the blade, forming an upper and lower circulating flow.
Tangential flow
In the container without baffle, the fluid rotates around the axis. When the flow rate is high, the liquid surface will form a vortex. The flow of fluid from the periphery of the blade to the blade area is very small, and the mixing effect is very poor.
Reactor agitator
The above three flow patterns usually exist at the same time;
Axial flow and radial flow play a major role in mixing;
Tangential flow should be suppressed - the use of baffles can weaken tangential flow and enhance axial and radial flow.
Classification and application of reactor agitators
Paddle type, propulsion 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
It is composed of blades, keys, collars and vertical shafts. Blades are generally made of flat steel or stainless steel or non-ferrous metal. The speed of paddle agitator is low, generally 20~80r/min. The diameter of paddle agitator is di/3~2/3 of the inner diameter of the reaction kettle. The paddle should not be too long. When the diameter of the reaction kettle is large, two or more paddles are used.
Main applications: the paddle agitator is suitable for liquid materials with high fluidity and low viscosity, as well as fibrous and crystalline solution. When the material layer is very deep, several rows of paddles can be installed on the shaft. Compared with the straight blade type, the folding blade type has less power consumption and lower operation cost, so the folding blade propeller is used more.
Paddle agitators cannot be used in gas-liquid dispersion operations for gas retention and refinement purposes.
The speed of paddle agitator is generally 20~100r/min, and its common parameters are shown in the table below:
Reactor agitator
2. propelling agitator
The propelling agitator can make the materials circulate in the reaction kettle during mixing. It mainly plays the role of volume circulation with small shearing effect and good up and down tumbling effect. When a larger flow rate is required, a draft tube is arranged in the reaction kettle.
The standard propelling agitator has three blades, and its pitch is equal to the propeller diameter D. The diameter of the propelling agitator is about 1/4~1/3300~600r/min of the inner diameter Di of the reactor. The agitator is usually made of cast iron and cast steel.
Reactor agitator
Features of the propelling agitator:
Axial flow agitator;
Large circulation and small mixing power;
Simple structure and convenient manufacture;
Commonly used in low viscosity fluids.
3. turbine agitator
The speed of turbine agitator is large, 300~600r/min. Straight blade and curved blade turbine agitators mainly produce radial flow, and folded blade turbine agitators mainly produce axial flow.
The main advantage of the turbine agitator is that when the energy consumption is small, the mixing efficiency is high, and the mixing produces a strong radial flow. Therefore, it is suitable for emulsions, suspensions, etc.
4. anchor mixer
It is applicable to the mixing of 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, that is, the frame agitator, to increase the mixing in the middle of the container.
Features of anchor agitator:
Simple structure and convenient manufacture;
Suitable for materials with high viscosity and large processing capacity;
It is easy to obtain large surface heat transfer coefficient;
It can reduce the occurrence of "wall hanging".
