1、 Classification of mixing process (Changsha Office of Shanghai kuosi Electronics Co., Ltd. specializes in the supply of Sanya brand D series mixer with high quality and high sales volume.)
From the viewpoint of stirring technology, fluid mixing can be divided into five basic mixing applications, and each stirring application can be divided into two types according to physical and chemical processes. As a result, there are ten basic mixing applications. Each basic mixing application has its own mixing characteristics, process requirements and amplification design criteria. In practical application, each stirring application often has several basic mixing applications. For example, flocculation and stirring process consists of liquid-liquid mixing and solid suspension.
2、 Classification of mixing blades (Shanghai kuosi Electronics Co., Ltd. Changsha office specializes in the supply of Sanya brand D series mixer with high quality and high sales volume.
Mixer is mainly composed of motor, reducer, mixing shaft and paddle blade. There are many forms of agitator blades, but no matter what kind of paddle forms, the shaft power consumption of the mixer has two parts: one is the liquid discharge generated by the blades, the other is the pressure head generated by the blades. The pressure head produced by the blade can be divided into two parts, namely static head and shear force; the static head must be overcome when the blade of mixer is operating, and the shear force makes the materials disperse and mix. Therefore, according to the discharge capacity, the ability to overcome static head and shear force, all blades can be divided into three basic types: flow type, head type and shear type. Each type of blade not only provides some basic function (for example, the basic function of flow type blade is to produce liquid discharge), but also provides two other functions (to generate shear and overcome static head). According to the different mixing requirements of different mixing projects, a reasonable blade form is selected, so that the matching of liquid discharge, static head and shear provided by the mixing blade can meet the mixing requirements of the mixing process to a large extent. If solid suspension and miscible liquid mixing, the blade is required to provide large liquid discharge and low shear. For gas-liquid dispersion, the blades are required to provide shear, liquid discharge and static pressure at the same time. The classification of mixing blades can also be divided into two types: axial flow blades and radial flow blades. The so-called axial-flow blade refers to that the main discharge direction of the blade is parallel to the mixing shaft, and the screw propeller blade is a typical axial-flow blade; the so-called radial blade means that the main discharge direction of the blade is vertical to the mixing axis. The impeller with "Sabre" shape blade, mixing energy consumption with 450 inclined flat blade axial impeller, small to medium, the flow generated is the dominant axial type, to ensure the very effective volume of mixing Zui is economic. The flow generated by the impeller is the main water pump effect. The impeller is ideal for most applications, leading to axial flow with radial flow and generating shear disturbance. In Non Stick media, especially those that need high speed and low energy consumption. For example, it is used for suspension or heat exchange. When the inclined blade runs at low speed, liquid-solid suspension is produced. At low speed, very weak or medium level disturbance will be generated, resulting in higher disturbance. This basic agitator blade is usually suitable for flocculation mixing with low shear coefficient for some simple agitation. Mixing is effective.
The propeller type blade is economical for small volume stirring. In viscous free media, traditional blades suitable for gas liquid exchange and heat exchange for solids, mixtures and emulsions are of medium level.
It produces radial flow with high resistance and energy consumption, and is specially used for special applications. Disturbance. Due to its weight, this kind of blade only uses small diameter and often runs at high speed (directly driven by motor)
3、 Basic principles and parameters of fluid mixing (Shanghai kuosi Electronics Co., Ltd. Changsha office specializes in the supply of Sanya brand D series mixer with high quality and high sales volume.
Mixer is determined by many parameters. It is impossible to describe a mixer with any single parameter. Shaft power (P), blade discharge (q), head (H), blade diameter (d) and mixing speeda (n) are the five basic parameters to describe a mixer.
The discharge volume of the blade is directly proportional to the flow standard of the blade itself, the first power of the blade speed and the third power of the blade diameter.
The shaft power consumed by stirring is directly proportional to the specific gravity of the fluid, the power criterion of the blade itself, the third power of the rotating speed and the fifth power of the blade diameter.
Under certain power and blade form, the discharge capacity (q) and head (H) can be adjusted by changing the matching of diameter (d) and rotating speed (n), that is, the mixer with large diameter blades and low speed (ensuring the same shaft power) produces higher flow effect and lower head, while small diameter blades with high speed produce higher head and lower head Mobility.
In a stirred tank, the way to make the pellets collide with each other is to provide sufficient shear rate. From the view of stirring mechanism, it is because of the existence of fluid velocity difference that the fluid layers are mixed with each other. Therefore, the shear rate of fluid is always involved in the mixing process. Shear stress is a kind of force, which is the real cause of bubble dispersion and droplet breakup in stirring applications.
It must be pointed out that the shear rate of fluid in the whole stirred tank is not the same. The results show that there are at least four shear rate values in a stirred tank
experiment
