Introduction
In laboratory and industrial applications, dispersion is a critical step in handling materials in many industries. The dispersion effect is directly affected by the speed range of the equipment, the shape of the dispersion disk and the matching of the container. Proper selection can help improve dispersion efficiency, ensure material uniformity and stability, and reduce energy consumption and operational risks. This article will explore the matching relationship between these factors from a technical perspective.
Speed range considerations
Rotational speed is the main parameter that affects the dispersion energy input. Typically, the speed range is determined based on the viscosity of the material, the target particle size and the throughput. Low-viscosity materials can be dispersed at lower speeds, while high-viscosity systems often require higher speeds to overcome cohesion. Too low a speed can lead to inadequate dispersion, while too high a speed can introduce too much heat or cause splashing. It is recommended to determine the appropriate rotational speed range through preliminary tests and estimate the required shear rate for dispersion with reference to the following equation:
γ = (π × D × N) / (60 × h)
Among them γ is the shear rate (unit: s⁻¹), D is the diameter of the dispersion disc (unit: m), N is the rotation speed (unit: rpm), and h is the gap between the dispersion disc and the bottom of the container (unit: m). This formula helps to quantify the shear effect at different rotational speeds and provides a theoretical basis for type selection.
Dispersion disk form
The shape of the dispersion disk determines the flow field structure and shear mode. Common forms include serrated discs, disc types, and blade types. The serrated disc produces strong turbulence through the toothed structure of the edge, which is suitable for the rapid dispersion of medium and high viscosity materials; The disc type provides a more uniform radial flow and is suitable for gentle dispersion of medium and low viscosity materials. The vane type promotes axial circulation and is suitable for applications where good mixing is required. Selection is based on material characteristics and process goals, such as when high-shear crushing aggregates are required, serrated discs are often the right choice.
| Dispersion disk form | Applicable scenarios |
| Serrated discs | Medium to high viscosity, strong shear required |
| Disc type | Medium to low viscosity, uniform flow is required |
| Blade type | Axial mixing needs to be strengthened |
Container matching principles
The geometry of the container has a significant impact on the dispersion effect. The ratio of the container diameter to the diameter of the dispersion pan is usually recommended between 2:1 and 3:1 to ensure an efficient circulating flow. The bottom shape of the container should be flat or slightly curved to avoid material deposition caused by dead corners. In addition, the level height should cover at least 1.5 times the diameter of the dispersion disc to ensure sufficient immersion depth. Mismatched containers can cause insufficient vortices or excessive splashing, affecting dispersion uniformity.
Comprehensive selection suggestions
Systematic thinking should be followed when selecting: first, the required shear strength should be determined according to the material characteristics and process requirements, so as to preliminarily select the rotation speed range and dispersion disc form; Then, the container size is selected according to the processing volume, and the matching degree is verified. Finally, the optimization parameters are verified by experiments. It is recommended to record the dispersion effect under different conditions to form internal reference data. Continuous attention to industry standard updates and technological progress will help improve the scientificity and reliability of selection.
References
1. The relationship between rotational speed and shear rate refers to the stirring flow field analysis in fluid mechanics-related textbooks.
2. The classification of dispersed disk forms is based on the comparative study of flow field patterns in several published technical articles.
3. The principle of container matching synthesizes the recommendations of the size ratio of container to agitator in many domestic and foreign industry standards.