What is a Hydrapulper Rotor？

The hydrapulper rotor as a high-speed rotating impeller, can generate powerful eddies and mechanical shearing forces. It is an important component of a hydrapulper and is used to break down and dissociate waste paper, pulp board and other materials into single fibers, and to separate impurities and fibers. The hydrapulper itself is a core piece of equipment in the modern pulp and paper industry and waste paper recycling field, working in conjunction with its internal rotor to break down waste paper raw materials into pulp.
Hydraupulper is a commonly used equipment for breaking waste paper or commercial pulp in the papermaking process. Its main components include rotor, tank, transmission mechanism, screen plate, and motor, among which the rotor is the main factor affecting pulp quality and energy consumption.

Main Types of Hydrapulper Rotors

At present, many domestic enterprises use vertical hydraupulper impellers, many of which are Vokes rotors (also known as rotor impellers) and their locally improved energy-saving Vokes impellers. This type of pulper impeller is placed at the center of the tank, and there are multiple guide plates arranged around the tank.

The Structure and Working Principle of the Vokes Hydrapulper Rotor

The traditional Vox impeller has 8 flat wing shaped blades, as shown in Figure 1. The diameter of the impeller is generally controlled between 1/3 and 1/2 of the diameter of the slot tank, and each blade simultaneously bears the role of the pulping plate and the circulating pulp flow; Low blades are set up on the periphery to mainly serve the purpose of fragmentation, while there are higher blades in the central area After high-speed rotation, turbulent regions are generated around the impeller to promote fiber disintegration.

Figure 1: Vokes Rotor

The high-speed pulp flow inside the tank is mainly composed of two flow states: the material is thrown towards the peripheral area of the tank by the action of blades near the center of the rotor, flows upward along the wall from the bottom due to resistance, and then flows back to the center area of the hydrapulper rotor through heavy force from the peripheral area of the upper part, forming a vertical circulation flow from bottom to top, namely vortex flow;

At the same time, due to the circular rotation of the hydrapulper rotor, the material in the horizontal plane inside the groove is driven to form a horizontal circular flow, that is, a circulation. The pulp velocity near the groove wall is lower than that in the central area, and there is a speed difference between the two, causing friction between the pulp Thus achieving the disintegration of the pulp, which is the function of the circulation. However, the operating flow state of the vortex is more intense compared to the circulating flow, and its flow state greatly increases the chance of friction and collision between the pulp. Therefore, it plays the main hydraulic crushing effect when crushing pulp, and the flow direction of the pulp is shown in Figure 2.

Figure 2

Effect of Vox Hydrapulper Rotor Structure on Energy Consumption

The overall shape of the Vox impeller is flat, and due to its smaller size, it cannot form an effective vortex flow state. Therefore, its hydrapulper rotor size is generally larger to ensure that sufficient vortex flow state can be formed during operation to achieve the expected fragmentation effect. When larger impellers operate, they will generate significant energy consumption, with more energy loss in the circulating flow state. Due to the limited effect of circular constant velocity circulation on the disintegration of pulp, energy consumption does not contribute much to the disintegration effect. In order to effectively utilize the circulating flow state, 3-6 guide plates are generally installed on the traditional waste paper pulping machine cylinder to change the single circulating flow state. Although the friction between the pulp flows is enhanced by disrupting the circulation flow state, this also increases energy consumption, causing the problem of high energy consumption in traditional pulpers.