Maintenance and troubleshooting of mud cleaner

Mud cleaner is an indispensable and important equipment in the field of oil drilling and underground engineering construction. It can effectively separate the solid-phase particles in the mud, recover useful drilling fluid, improve mud quality and reduce construction costs. However, long-term use and complex working environment will lead to various problems of mud cleaner, therefore, mastering its maintenance methods and troubleshooting skills is of great significance to ensure the stable operation of the equipment, prolong the service life and improve the construction efficiency.

一.Structure and working principle of mud cleaner

Mud cleaner is mainly composed of vibrating screen, hydrocyclone, slurry supply pump, base and bracket. Its working principle is: through the slurry supply pump will be conveyed to the hydrocyclone, in the cyclone, the slurry in the centrifugal force to achieve the initial separation of solid and liquid, the larger particles of solid-phase material is thrown to the inner wall of the cyclone, and along the inner wall downward movement, from the bottom flow outlet; containing smaller particles of the liquid phase from the top of the cyclone out of the overflow port. The material discharged from the bottom outlet of the cyclone enters into the vibrating screen, which further separates the solid particles from the slurry through high-frequency vibration, and the material on the top of the screen is drier solid particles, while the material under the screen is cleaner slurry, which can be recycled again.

二.Maintenance of the mud cleaner

1.Daily maintenance

After daily operation, the mud cleaner surface and internal residual mud and solid-phase particles should be cleaned in time. Use high-pressure water gun to rinse the vibrating screen mesh, hydrocyclone interior and pipeline to ensure that there is no mud caking and clogging phenomenon. Pay particular attention to cleaning the vibrating screen’s vibrating motor, shaker and other parts to prevent mud from entering the motor interior and damaging the electrical components. Check whether the vibrating screen mesh is broken, deformed or blocked. If the screen mesh is broken, it should be replaced in time to avoid larger particles of solid-phase substances from entering the mud under the screen and affecting the cleaning effect of the mud; if the screen mesh is clogged, it can be unclogged using a special screen cleaning tool, and the screen mesh can be dismantled and thoroughly cleaned if necessary. Check whether the cyclone nozzle and overflow pipe of the hydrocyclone are worn, if the wear is serious, it will lead to a decline in the separation efficiency of the cyclone, and the worn parts should be replaced in time. In addition, it is also necessary to check whether the seals of the slurry supply pump are intact, whether there is any leakage phenomenon, and whether the impeller of the pump is worn out to ensure the normal operation of the slurry supply pump. Lubricate the vibrating motor bearings and exciter bearings of the vibrating screen, as well as the bearings of the slurry supply pump on a regular basis according to the requirements of the instruction manual of the equipment. After lubrication, check whether there is grease leakage in the lubrication part, if there is leakage, it should be dealt with in time.

2.Regular Maintenance

Check whether the vibration frequency and amplitude of the vibrating screen meet the requirements of the equipment, if not, it can be adjusted by adjusting the counterweight block of the vibrating motor or the motor speed. Check whether the connecting bolts between the screen box and the base of the vibrating screen are loose. Check whether the installation of hydrocyclone is firm, whether the connection parts are well sealed, if there is any looseness or poor sealing, it should be dealt with in time. Regularly replace the wearing parts of the slurry cleaner, such as the vibrating screen mesh, the cyclone nozzle of the hydrocyclone, the overflow pipe, and the seals and impellers of the slurry supply pump. According to the frequency of use and working environment of the equipment, set a reasonable replacement cycle for wearing parts. Check whether the insulation resistance of the slurry supply pump motor and vibration motor meets the requirements, and check whether the electrical components in the electrical control cabinet are working normally, whether the wiring is firm, and whether there is any loosening and aging. Clean the dust and debris in the electrical control cabinet to ensure good heat dissipation of the electrical system and prevent equipment shutdown due to electrical failure.

3.Long-term out-of-service maintenance

When the mud cleaner needs to be out of service for a long period of time, special maintenance should be carried out. Firstly, empty all the mud inside the equipment and clean it thoroughly to prevent the mud from drying up inside the equipment and damaging the equipment parts. Carry out anti-rust treatment on the vibrating screen mesh, hydrocyclone and other components, and anti-rust grease can be applied. Protect the electrical components of the equipment from moisture, such as using moisture-proof bags to seal them and placing desiccant. Regularly inspect the equipment to prevent it from being damaged during decommissioning.

三.The common failures and troubleshooting methods of mud cleaner

1.Vibrating screen failure

Vibration abnormal

Phenomenon: vibrating screen vibration when there is a violent shaking, excessive noise or uneven vibration and so on.

Cause analysis: it may be that the counterweight block of the vibrating motor is not installed correctly, the vibrating motor is damaged, the connecting bolts between the screen box and the base are loose, the screen mesh is not installed firmly, or the screen box is deformed.

Remedy: Firstly, check whether the counterweight block of the vibrating motor is installed symmetrically, and adjust the position of the counterweight block to make it meet the requirements; if the vibrating motor is damaged, the motor should be replaced in time. Check the connection bolts between the screen box and the base, and tighten them according to the specified torque. Reinstall the screen mesh, make sure the screen mesh is firmly installed and the tension is appropriate. If the screen box is deformed, correct or replace the screen box according to the deformation.

Screen clogging

Phenomenon: The slurry accumulates on the screen mesh and cannot pass through the screen mesh smoothly, resulting in a decrease in screening efficiency.

Cause analysis: the solid phase content of the slurry is too high, the screen mesh is not properly selected, there are debris on the surface of the screen mesh or the screen mesh has been in use for too long, resulting in the screen holes being worn out to a small size, and so on.

Remedy: Appropriately reduce the solid-phase content of the mud, which can be achieved by adjusting the mud treatment process or increasing the mud treatment equipment. According to the size of solid-phase particles in the slurry, select the appropriate mesh screen. Clean the debris on the surface of the screen mesh, and if the screen mesh is seriously worn, the screen mesh should be replaced in time.

Broken screen mesh

Phenomenon: cracks, holes and other damages appear on the screen mesh, resulting in solid-phase particles leaking into the slurry under the screen.

Cause analysis: unqualified quality of screen mesh, improper installation of screen mesh, slurry containing sharp solid-phase particles, abnormal vibration of vibrating screen. Remedy: Select screen mesh with qualified quality and install it according to the correct installation method. Pretreat the mud to remove the sharp solid-phase particles. If the screen mesh is broken due to abnormal vibration of the vibrating screen, the abnormal vibration fault should be ruled out first, and then replace the broken screen mesh.

2.Hydrocyclone Failure

Low Separation Efficiency

Phenomenon: The mud discharged from the bottom flow port of the hydrocyclone contains more fine particles, and the mud discharged from the overflow port has a high content of solids, and the separation effect is not good.

Cause analysis: wear and tear of the cyclone nozzle or overflow pipe, unstable or non-compliant slurry supply pressure, inappropriate concentration and viscosity of the slurry, incorrect installation angle of the cyclone, etc.

Remedy: Check the wear and tear of the cyclone nozzle and overflow pipe, and replace the worn parts in time. Install pressure gauge to monitor the slurry supply pressure, and make the slurry supply pressure stable within the range required by the equipment by adjusting the speed of the slurry supply pump or the outlet valve. According to the nature of the slurry, adjust the concentration and viscosity of the slurry to make it meet the working requirements of the hydrocyclone. Check the installation angle of the cyclone to ensure that it meets the requirements of the equipment installation instructions, and make timely adjustments if there is any deviation.

Underflow port blockage

Phenomenon: hydrocyclone underflow port slurry discharge is not smooth, or even completely blocked, resulting in the cyclone can not work properly.

Cause analysis: the solid-phase particles in the slurry are too large, the concentration is too high, or the cyclone nozzle calibre is too small, resulting in the accumulation of solid-phase particles in the underflow port blockage.

Remedy: Pre-treat the mud to remove the larger solid phase particles in it. Appropriately reduce the concentration of the slurry, or replace the cyclone nozzle with a larger calibre to ensure that solid-phase particles can be discharged smoothly. If the bottom flow port has been clogged, use a high-pressure water gun to flush the bottom flow port to unclog the clogged area.

The overflow port runs thick

Phenomenon: The slurry discharged from the overflow port of the hydrocyclone contains more large particles of solid-phase material.

Cause analysis: the working pressure of the cyclone is too high, the cyclone nozzle is badly worn, and the feed volume of the slurry is too large.

Remedy: Reduce the slurry supply pressure to meet the equipment requirements. Replace the worn cyclone nozzle to ensure the separation effect of the cyclone. Adjust the flow rate of the slurry supply pump to control the slurry intake to avoid insufficient separation of the cyclone due to excessive slurry intake.

3.Failure of the slurry supply pump

Insufficient flow

Phenomenon: The slurry flow output from the slurry supply pump does not meet the equipment requirements, resulting in insufficient supply of slurry to the hydrocyclone and affecting the overall efficiency of the slurry cleaner.

Cause analysis: the impeller of the pump is worn, the suction line of the pump is clogged, the speed of the pump is too low, and the seals of the pump are damaged resulting in leakage.

Remedy: Check the wear of the pump’s impeller, and replace the impeller in time if it is seriously worn. Clean the suction line of the pump to remove debris and clogging in the line. Check the motor speed of the pump to ensure that it meets the requirements of the equipment, if the speed is too low, the motor and transmission device should be checked for faults and repaired. Check the seals of the pump and replace the damaged seals to prevent the slurry from leaking and affecting the flow of the pump.

Insufficient pressure

Phenomenon: The mud pressure output from the slurry supply pump is too low to meet the working pressure requirements of the hydrocyclone.

Cause analysis: Similar to the cause of insufficient flow, impeller wear, clogged suction lines, and leakage of seals can lead to insufficient pump pressure. In addition, the pump outlet valve is not completely open, the pump head selection may also lead to insufficient pressure.

Remedy: Troubleshoot and deal with the above causes. Ensure that the pump outlet valve is fully open, check whether the pump head meets the actual working requirements, if not, should be replaced with the appropriate head of the slurry pump.

Abnormal pump vibration

Phenomenon: The slurry supply pump vibrates violently during operation, accompanied by abnormal noise. Cause analysis: the pump foundation is not firmly installed, poor alignment of the coupling between the pump and the motor, imbalance of the pump impeller, air leakage in the suction line of the pump, etc.

Remedy: Check the foundation of the pump to ensure that the foundation is firm and the ground bolts are not loose. Re-centre the coupling between the pump and the motor to ensure that the concentricity of both meets the requirements. Perform dynamic balance test and adjustment on the impeller, if the impeller is damaged, it should be replaced in time. Check the suction pipeline of the pump to ensure that the pipeline is well sealed without air leakage, if there is any air leakage, repair it in time.

Maintenance and troubleshooting of mud cleaner is a systematic and professional work, which requires operators to be familiar with the structure and working principle of the equipment, operate in strict accordance with the maintenance regulations, and have certain troubleshooting and processing capabilities. Through scientific and reasonable maintenance, it can reduce the occurrence of equipment failure, prolong the service life of the equipment, improve the efficiency and reliability of the equipment; to ensure that the mud cleaner is always in a good state of operation.