Hydrocyclone common five failure analysis and solution

As an efficient separation and classification equipment, hydrocyclone is widely used in many industries such as mining, chemical industry, environmental protection and so on, by virtue of its simple structure, small footprint, large processing capacity and other advantages. However, in the actual operation process, hydrocyclone often appear such as feed pressure fluctuations, clogging, abnormal underflow concentration and flow, overflow concentration and fineness abnormal, and spray or rope sand blasting nozzle and other problems. These failures not only affect the normal operation and separation efficiency of the equipment, but also may lead to production interruptions, increase maintenance costs, and even cause safety hazards. Therefore, in-depth analysis of the causes of these failures and the proposal of effective solutions are of great significance to guarantee the stable and efficient operation of hydrocyclones.

一.The feed pressure fluctuations

1.Failure phenomenon

In the hydrocyclone operation process, the feed pressure shows irregular and large fluctuations, sometimes the pressure suddenly rises, exceeding the rated working pressure of the equipment, resulting in increased vibration of the equipment; sometimes the pressure falls sharply, which makes the separation effect deteriorate, and can not meet the production requirements.

2.Causes analysis

Feed system instability: the unstable performance of the feed pump, such as fluctuations in the speed of the pump, impeller wear and tear, etc., will lead to uneven feed flow, which will cause fluctuations in the feed pressure. In addition, the arrangement of the feed pipe is unreasonable, there are too many elbows, valves, or the internal diameter of the pipe is not consistent, will also increase the resistance of the fluid flow, resulting in pressure fluctuations. Changes in material properties: When the concentration and particle size distribution of the material entering the hydrocyclone change significantly, it will affect the rheological properties of the fluid. For example, a sudden increase in material concentration will increase the viscosity of the fluid, increasing the resistance to flow, resulting in a rise in feed pressure; while the particle size becomes finer, may make the material in the pipeline to intensify the phenomenon of deposition, will also cause pressure fluctuations. Pipe blockage or leakage: If there is foreign matter blocking inside the feeding pipe, it will hinder the normal flow of materials and make the local pressure rise; while pipe leakage will lead to pressure drop. As the blockage or leakage situation changes, the feed pressure will fluctuate accordingly.

3.Solutions

Optimise the feeding system: choose the feeding pump with stable performance and even flow rate, and carry out regular maintenance and overhaul of the pump, and replace the worn impeller and seals in time. Reasonable design of the feed pipe, minimise the number of elbows and valves, ensure that the inner diameter of the pipe is consistent, and reduce the resistance to fluid flow. Pressure sensors and flow controllers can be installed on the pipeline to monitor and adjust the feed pressure and flow in real time to ensure the stability of the feed. Control the nature of materials: strengthen the monitoring and management of incoming materials, and strictly control the concentration and particle size distribution of materials. Before the material enters the hydrocyclone, set up the necessary pre-treatment links, such as through the mixing equipment to make the concentration of the material uniform, the use of screening equipment to remove oversized particles. When the nature of the material changes, adjust the operating parameters of the hydrocyclone in time to adapt to the new working conditions. Check and maintain the pipeline: inspect the feeding pipeline regularly and clean the foreign matter and sediment in the pipeline in time to prevent blockage. At the same time, check the connection parts of the pipeline to ensure good sealing, and find leakage in time.

二.Tthe hydrocyclone clogging

1.Failure phenomenon

hydrocyclone inlet, underflow or internal flow channel blockage, resulting in a reduction in the feed flow, underflow and overflow discharge is not smooth, the equipment operating sound abnormal, separation efficiency decreased significantly.

2.Causes analysis

Material factors: the material contains large particles, fibrous substances or viscous impurities, easy to accumulate in the cyclone inlet, bottom flow mouth or internal narrow parts, resulting in blockage. In addition, the material concentration is too high, will also increase the risk of clogging, because the high concentration of material in the flow process is easy to form agglomerates, hindering the flow of fluid. Improper operating parameters: too high or too low feed pressure will affect the flow state of the material in the cyclone. When the pressure is too high, the material flow rate is too fast, which may cause the larger particles to directly hit the inner wall of the cyclone or the bottom flow mouth, resulting in clogging; too low a pressure will result in too long a residence time of the material in the cyclone, prone to sedimentation and clogging. Underflow port diameter is too small, will also limit the discharge of materials, increasing the possibility of clogging. (C) Solution

Strengthen the material pretreatment: Before the material enters the hydrocyclone, increase the pretreatment equipment such as filtration, screening, etc., to remove the large particles, fibrous materials and viscous impurities. Vibrating screens, filters and other equipment can be used to preliminarily screen and purify the material. At the same time, the material concentration is reasonably controlled to avoid excessive concentration leading to clogging. The material concentration can be controlled in a suitable range by adjusting the amount of feed and the proportion of dilution water. Optimise the operating parameters: according to the nature of the material and the performance of the equipment, reasonably adjust the feed pressure and the diameter of the underflow port. In the early stage of equipment operation, the best operating parameters are determined through tests and fine-tuned according to the actual situation during operation.

三.Abnormal bottom stream concentration and flow

1.Failure phenomenon

Bottom stream concentration is too high or too low, beyond the normal range, affecting the processing effect of the subsequent process; bottom stream flow is unstable, sometimes large and sometimes small, resulting in the production process is difficult to control.

2.Causes analysis

Changes in operating parameters: Changes in operating parameters such as feed pressure, feed flow rate, bottom flow port diameter, etc., will directly affect the concentration and flow rate of the bottom stream. For example, an increase in feed pressure will increase the bottom flow rate and reduce the concentration; expansion of the diameter of the bottom flow port will also lead to an increase in the bottom flow rate and a decrease in concentration. Change in material properties: When the material’s particle size distribution, density, concentration and other properties change, it will affect the separation effect of the material in the cyclone, which will lead to abnormal underflow concentration and flow. Such as material particle size coarsening, will make more coarse particles into the underflow, resulting in increased underflow concentration; material concentration is reduced, the underflow flow will be reduced, the concentration is also reduced accordingly. (C) Solution

Precise adjustment of operating parameters: establish a perfect monitoring system for operating parameters, real-time monitoring of key parameters such as feed pressure, flow rate, bottom flow concentration and flow rate. According to the requirements of the production process and the nature of the material, determine the best combination of operating parameters through testing, and operate in strict accordance with the parameters. When abnormal bottom flow concentration and flow rate are found, the reasons are analysed in time and the relevant parameters are adjusted. For example, when the concentration of bottom flow is too high, you can appropriately increase the feed pressure or expand the diameter of the bottom flow port; when the bottom flow rate is unstable, check whether the feed flow rate is stable, and make corresponding adjustments. Monitor the nature of materials: strengthen the detection and analysis of material properties, and grasp the changes in particle size distribution, density, concentration and other materials in a timely manner. When the material nature of large changes, adjust the operating parameters of hydrocyclone in advance to adapt to the new material characteristics.

四. Abnormal overflow concentration and fineness

1.Fault phenomenon

The solid particle content in the overflow is too high, and the concentration exceeds the normal range, affecting the product quality; the particle size in the overflow does not meet the requirements, the fineness does not meet the standard, and cannot meet the needs of subsequent processes.

2.Cause analysis

Improper feed pressure and flow rate: If the feed pressure is too low, the centrifugal force of the material in the cyclone will be insufficient, resulting in the inability to effectively separate fine particles, thereby increasing the overflow concentration and coarsening the fineness; if the feed flow rate is too large, the flow field in the cyclone will be turbulent, the separation effect will be poor, and the overflow concentration and fineness will also be abnormal.

Improper overflow port size: If the overflow port diameter is too large, more fluid containing solid particles will enter the overflow, resulting in an increase in the overflow concentration; if the overflow port diameter is too small, it will limit the discharge of fine particles and make the overflow fineness coarsening.

Material property fluctuations: Fluctuations in the particle size distribution, density, concentration and other properties of the material will change the separation behavior of the material in the cyclone.

3.Solution

Adjust operating parameters: According to the material properties and production process requirements, reasonably adjust the feed pressure and flow rate. Determine the optimal pressure and flow rate values through experiments and keep them stable during operation. When the overflow concentration and fineness are found to be abnormal, adjust the feed pressure and flow rate in time to observe the changes in the separation effect. For example, when the overflow concentration is too high, the feed pressure can be appropriately increased to enhance the centrifugal force and promote the separation of fine particles; when the overflow fineness is not up to standard, the feed flow rate can be adjusted to optimize the flow field in the cyclone.

Optimize the overflow port size: According to the design parameters and actual operation of the hydrocyclone, optimize the overflow port size. If the overflow concentration is too high, the overflow port diameter can be appropriately reduced.

Stabilize material properties: Strengthen the management of material sources and try to ensure the stability of material properties. Before the material enters the hydrocyclone, fully mix and homogenize the material to reduce the fluctuation of material properties. When the material properties change, adjust the operating parameters of the hydrocyclone in time to adapt to the new material properties.

5. Spray or rope-shaped sandblasting nozzles

1.Fault phenomenon

The sandblasting nozzle of the hydrocyclone has spray or rope-shaped discharge, which is different from the normal uniform discharge state, affecting the normal operation and separation effect of the equipment.

2.Cause analysis

Sandblasting nozzle wear: During long-term use, the sandblasting nozzle is washed by high-speed fluid and solid particles and will gradually wear out. The wear and expansion of the inner hole of the sandblasting nozzle, the damage of the edge or the increase of the surface roughness will lead to uneven discharge, spray or rope-shaped phenomena.

Material blockage: If there is material blockage inside the sandblasting nozzle, it will change the flow direction and speed of the fluid, causing abnormal discharge. The blockage may be large particles, impurities in the material, or materials deposited when the equipment is shut down.

Abnormal operating parameters: Abnormal operating parameters such as too high or too low feed pressure and unstable flow rate will affect the flow state of the material in the sandblasting nozzle. Too high pressure will cause the fluid to spray too fast and form a spray; too low pressure may cause poor discharge and form a rope.​

3.Solution​

Replace the worn sandblasting nozzle: Check the wear of the sandblasting nozzle regularly. When the sandblasting nozzle is found to be seriously worn, replace it in time. Select a sandblasting nozzle with good quality and strong wear resistance, and match and install it according to the model and specifications of the equipment. After replacing the sandblasting nozzle, debug the equipment to ensure normal discharge. ​

Clean the blockage of the sandblasting nozzle: When the sandblasting nozzle is blocked, stop the equipment and disassemble the sandblasting nozzle for cleaning. You can use tools such as high-pressure water guns and wire brushes to remove the blockage inside the sandblasting nozzle. During the cleaning process, pay attention to protecting the inner hole and edge of the sandblasting nozzle to avoid secondary damage. After cleaning, check and test the sandblasting nozzle, and reinstall it after confirming that it is unobstructed. ​

Adjust the operating parameters: According to the design requirements of the sandblasting nozzle and the operation of the equipment, reasonably adjust the feed pressure and flow rate. Keep the feed pressure and flow rate stable to avoid being too high or too low. When the sandblasting nozzle is found to be abnormal, improve it by adjusting the operating parameters. For example, when spray-like discharge occurs, the feed pressure can be appropriately reduced; when rope-like discharge occurs, the feed pressure can be increased or the flow rate can be adjusted.

The normal operation of hydrocyclones in industrial production is crucial to improving production efficiency and ensuring product quality. Large fluctuations in feed pressure, blockage, abnormal underflow concentration and flow, abnormal overflow concentration and fineness, and spray or rope-shaped sandblasting nozzles are common faults in the operation of hydrocyclones. In actual production, the operation monitoring and maintenance management of hydrocyclones should be strengthened, potential problems should be discovered and handled in a timely manner, and experience should be continuously summarized to improve the operating reliability and economic benefits of the equipment.