Blender main classification, basic knowledge and selection

The stirrer is a device that forces convection of liquid and gaseous media and mixes evenly.

The basic composition of the mixer: impeller, stirring shaft, motor, accessories (reducer, rack, etc.).

The classification of the stirrer is mainly classified according to the shape of the impeller, such as frame stirrer, anchor stirrer, propeller stirrer, double stirrer, vane stirrer, turbine stirrer, propeller stirrer, open Turbo mixers and so on. In addition, there are side-entry stirrers, cantilever stirrers, variable-frequency stirrers, etc.

Different agitators in the form of impellers can meet different agitation requirements. For example, a turbo-stirrer is generally constructed by mounting 2 to 4 flat or curved blades on a horizontal disc. The ratio of the outer diameter, width and height of the blade is generally 20:5:4, and the circumferential speed is generally 3 to 8 m/s. The turbine generates a highly turbulent radial flow during rotation, which is suitable for the dispersion of gas and immiscible liquids and the liquid-liquid reaction process. The viscosity of the liquid to be stirred is generally not more than 25 Pa•s.

According to the physical properties of the medium, the capacity, the purpose of the mixing operation and other factors, determine the appropriate impeller form, size, speed and other parameters, so that the stirrer to maximize the use of mixing operations to meet the needs.

The design choice of stirring device is closely linked with the purpose of mixing. The various stirring processes need to be realized by different stirring devices. When designing and selecting the type, the agitator type, motor power and stirring speed must be determined according to the purpose and requirements of the process for the agitation operation, and then the speed reducer and the machine must be selected. Frames, agitator shafts, shaft seals and other components. The specific steps are as follows:

1. According to the process conditions, stirring purposes and requirements, choose the type of stirrer, select the stirrer type should fully grasp the dynamic characteristics of the stirrer and stirrer in the stirring process of the flow state and the causal relationship between the various stirring purposes.

2. According to the determined agitator type and the flow state produced by the agitator during the agitation process, the control requirements for the agitation mixing time, the settling velocity, and the dispersion degree of the process, through the experimental means and computer simulation design, determine the motor power, stirring Speed, mixer diameter.

3. Select the reducer model from the reducer selection table according to the motor power, stirring speed, and process conditions. If the reducer is selected according to the actual working torque, the actual working torque should be less than the allowable torque of the reducer.

4. According to the output shaft head d of the reducer and the supporting way of the agitating shaft, select the rack and coupling with the same model and specifications as d. 5. Select the size, installation space, working pressure and working temperature of the agitator shaft head according to the frame. Shaft seal type 6. In accordance with the installation form and structural requirements, design and selection of stirring shaft structure type, and check the strength and rigidity.

If the design is based on a rigid shaft, n/nk ≤ 0.7 when the strength is satisfied

According to the flexible shaft design, n/nk>=1.3 under the condition of satisfying strength

7. According to the rack's nominal heart DN, axis type and pressure rating of the stirring shaft, choose to install the bottom cover, flange base or flange flange. 8. According to the support and anti-vibration conditions, determine whether to configure the auxiliary support.

In the above selection process, the combination and configuration of the stirring device can be referred to (a schematic diagram of the agitation device design selection process). The key dimension of the connection between each component in the configuration process is the size of the shaft head, and the components with the same axial head size can in principle be mutually compatible. Change, combination.

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