In the oil drilling industry, mud needs to be constantly recycled during the drilling process, and it will inevitably be mixed with sand particles of various sizes. If these sand particles are not removed in time, the consequences will be unimaginable. On the one hand, they will aggravate the wear and tear of mud pumps, drilling rods and other equipment, shortening the service life of the equipment. On the other hand, mud with high sand content will also affect the performance of drilling fluid, reduce its lubrication and cooling effect, and increase the resistance in the drilling process, thus affecting the drilling efficiency and quality. Desander can effectively remove the sand particles in the mud through efficient separation technology, ensure the cleanliness of the mud, and guarantee the smooth progress of drilling operations.
In the field of sewage treatment, desander is also a crucial part. Sewage usually contains a large number of sand, suspended solids and other impurities, if not through the desanding process directly into the subsequent treatment process, will cause serious damage to the sewage treatment equipment, such as clogging pipes, wear and tear of the pump impeller, etc. . Moreover, these impurities will also affect the growth and metabolism of microorganisms, reduce the efficiency and effectiveness of sewage treatment, resulting in substandard water quality. Desander can be in the front end of sewage treatment, most of the sediment and larger particles of impurities separated out, reduce the burden of subsequent treatment equipment, improve the stability of the operation of the entire sewage treatment system and processing capacity.
In addition to oil drilling and sewage treatment, desander is also widely used in construction engineering, mineral mining, food processing and many other industries. In the concrete mixing plant of construction engineering, the desander can remove the soil and impurities in the sand and gravel raw materials to ensure the quality and strength of concrete; in mineral mining, it helps to improve the grade and recovery rate of the ore; in the food processing industry, it can ensure the purity and taste of the products. It can be said that in any industrial scenario involving liquid or slurry processing and the presence of sediment impurities, desander plays an indispensable role, is to ensure smooth production, improve product quality, reduce production costs of key equipment.
一.Daily maintenance points of the desander
Routine maintenance is the key to long-term stable and efficient operation of desander. Routine maintenance mainly covers the three key aspects of meticulous inspection before use, close monitoring during operation and in-depth maintenance after shutdown.
1.Pre-use inspection
In each start before the desander, comprehensive and detailed inspection is to ensure that the equipment is the basis for normal operation. Check, need to carefully check the various parts of the equipment, first of all, pay attention to the various screws whether there is a loose phenomenon, whether it is firmly fixed. Loose screws may lead to equipment in the operation process of component displacement, vibration intensification and other problems, and even cause equipment failure.
Small vibrating screen motor as an important part of the desander, whether its wiring meets the requirements is crucial. It is important to check whether the wiring is firm, with no breakage, short circuit and so on. The wiring that does not meet the requirements may lead to the danger that the generator can not start normally, run abnormally or even short-circuit fire. At the same time, also need to check whether the motor shaft is normal, whether the rotation is flexible, whether there is no stagnation phenomenon. You can manually rotate the rotor shaft, feel the smoothness of its rotation, if you find the rotor shaft stagnation, you should promptly investigate the cause, may be bearing damage, foreign objects into the problem, you need to repair or replace the relevant parts before starting the equipment.
In addition to the above checks, the opening of the gate should not be ignored. To ensure that the gate can open and close normally, without jamming, leakage and other problems. Failure of the gate may lead to uncontrolled liquid flow and affect the normal operation of the desander. If the gate is found to have problems, it should be repaired or replaced in time to ensure its sealing performance and operational flexibility. In the inspection process, if any abnormal sound or failure is found, it must be immediately shut down for troubleshooting and repair to confirm that the equipment is normal before use.
2.Close monitoring during operation
Desander normal work, the pressure range is usually 0.2 – 0.4MPa, but this is not absolute, according to the viscosity of the drilling fluid, density, sand content and other specific conditions flexible adjustment. Too high or too low pressure will adversely affect the desanding effect. When the pressure is too high, it may cause the internal parts of the equipment to withstand excessive pressure, accelerating wear and tear, and even cause equipment damage; too low a pressure may not be able to provide sufficient centrifugal force, so that the sand particles can not be effectively separated. Therefore, the operator should always pay attention to the value of the pressure gauge, and once abnormal pressure is found, the reason should be analysed and adjusted immediately.
The adjustment of the size of the sand discharge port (bottom flow port) is also critical. It should be adjusted to a suitable size according to the actual working conditions, so that the bottom stream drilling fluid is discharged in the form of umbrella jet. Such a jetting state indicates that the desander is in good working condition and can effectively discharge the sand particles. If the bottom stream is not an umbrella jet, it may mean that the sand discharge port is clogged or improperly adjusted, and needs to be cleaned or re-adjusted in time. Appropriately increase the inlet flow can make the overflow particle size smaller, so as to achieve the maximum removal of solid phase purpose. However, the increase in flow rate also needs to be moderate, too large a flow rate may overload the equipment, affecting the effect of sand removal and equipment life.
In addition to pressure and grit removal port adjustment, close attention should be paid to the flow control of the equipment. It is necessary to ensure that the inlet flow rate is stable and avoid large fluctuations. Unstable flow rate may lead to disturbances in the flow field inside the desander, affecting the separation effect of sand particles. At the same time, the operating sound and vibration of the equipment should be checked regularly. The normal operation of the desander has a smooth sound and small vibration amplitude. If there is an abnormal sound or vibration intensification, it may be that the internal parts of the equipment are loose, wear and tear or other failures, you should immediately stop the machine to check, find out the root cause of the problem and solve it in time.
3.Deep maintenance after shutdown
After stopping the machine, timely and comprehensive flushing of the desander with water is the first task. Flushing can remove the residual sediment and impurities inside the equipment to prevent them from drying out inside the equipment and affecting the next use. When flushing, make sure that all parts can be flushed, including the cyclone, vibrating screen, pipeline and so on. For some dirt that is difficult to rinse off, you can use a soft brush or other tools to gently scrub, but be careful to avoid damaging the surface of the equipment.
The wear and tear of the equipment also needs to be carefully checked. Focus on checking the inner wall of the cyclone, the sand discharge port, the screen of the vibrating screen and other wearable parts. Wear on the inner wall of the cyclone may cause its separation effect to decrease, and wear on the sand discharge port may affect the sand discharge effect. If the screen mesh is found to be damaged, it should be replaced in time so as not to affect the efficiency of sand removal. At the same time, it is also necessary to check the connection parts of the equipment, such as screws, flanges, etc., to see if there is any looseness, damage phenomenon, such as the need for timely tightening or replacement.
The lubrication of the equipment should not be neglected. Regularly on the equipment bearings, shafts and other rotating parts to replenish the grease, can reduce the friction between the components, reduce wear and tear, and extend the service life of the equipment. Generally speaking, the oil cups at both ends of the reel shaft should be filled with grease once a week, and the oil cup above the vibrating shaft bearing seat should be filled with molybdenum disulfide grease once a shift. When filling grease, pay attention to the right amount, too much or too little are not conducive to the normal operation of the equipment. The motor should also be regularly checked and cleaned, the shell shall not accumulate dust, and the motor shall not be cleaned by water jet, so as not to affect the performance and service life of the motor.
二.Desander troubleshooting
1.Discharge bonding problem
In the operation of the desander, bonding at the discharge outlet, i.e., bonding of the liquid and solid phases, occurs from time to time. The main cause of this problem is solid phase overload. When too many solid-phase particles enter the desander, exceeding the processing capacity of the equipment, it is easy to cause the discharge outlet to be blocked and bonded.
For this failure, the following solution measures can be taken: first, consider increasing the number of desanding cyclones. By increasing the number of cyclones, the overall processing capacity of the equipment can be improved, and the solid phase content can be effectively reduced. Secondly, the vibrating screen should be carefully checked for damaged screen cloth. If the screen cloth is damaged, it will make the larger particles of solid-phase material directly into the desander, increasing the processing burden of the equipment. Once the screen cloth is found to be damaged, it should be replaced with a new one in time. In addition, it is also necessary to check whether the vibrating screen bypass is closed. If the bypass is not closed, part of the mud not treated by the vibrating screen will directly enter the desander, resulting in too high a solid-phase content.
2.Excessive liquid loss
Excessive liquid loss is also one of the common faults of desander, and its causes are more complex. First of all, the supply hydraulic head is too low is an important factor. Liquid supply pump inlet partially clogged, air in the pump, pump speed is too slow, impeller size is too small, pump discharge line has a throttle, pump steering error and solid deposits in the line, etc., may lead to the supply of insufficient hydraulic head. In a wastewater treatment plant, the supply hydraulic head was reduced because the inlet of the supply pump was clogged with debris, making the liquid loss of the desander increase dramatically and affecting the normal operation of the equipment.
Secondly, too large a nozzle can also lead to excessive liquid losses. If the nozzle size exceeds the design requirements of the equipment, it will make the liquid injection speed and flow rate change, thus increasing the liquid loss. In addition, wear and tear of the inner barrel or nozzle is also a common cause. Prolonged operation under high pressure, normal wear and tear, and incorrect installation of the inlet can lead to wear and tear of the inner barrel or nozzle, which affects the sealing performance and efficiency of the equipment, which in turn leads to excessive liquid loss.
For the problem of excessive liquid loss, the following solutions can be taken: for the supply of hydraulic head is too low, a strainer should be installed at the inlet of the liquid supply pump to prevent debris from entering the pump body and causing clogging; check and adjust the pump’s operating status, such as correcting steering errors, increasing pump speed (if diesel-driven), increasing the size of the impeller, checking and cleaning the throttling part of the discharge line, cleaning the line and installing near the suction end of the butterfly valve near the suction end to ensure that the supply pressure head is stable and meets equipment requirements. For the problem that the nozzle is too big, you can choose the right size nozzle according to the actual working conditions of the equipment and processing requirements, reduce the nozzle size, reduce the amount of liquid injection, thus reducing the liquid loss. If the problem is caused by wear and tear of the inner barrel or nozzle, it can be taken to reduce the pump speed or reduce the size of the impeller to reduce the pressure and wear and tear inside the equipment; reinstall the nozzle to ensure that the installation position is correct and the sealing is good; for the serious wear and tear of the inner barrel or the nozzle, it should be replaced with new parts in time.
3.Nozzle does not liquid
Desander nozzles without liquid is also a relatively common failure, may be clogged nozzles or inlet pressure is too high. This failure may be triggered by such factors as dirty slurry, discontinuous operation of solid control equipment, drying of the slurry in the desander cyclone, rupture of the vibrating screen screen cloth or bypass of the vibrating screen, too fast pump speed, too large an impeller size, and incorrect position of the throttle valve. In a concrete mixing plant of a construction project, the excessive impurities in the mud led to the clogging of the desander nozzles, which prevented the normal discharge of liquid, affecting the quality and progress of concrete production.
When the nozzle does not dispense liquid, the following coping strategies can be adopted: first, switch off the equipment, unclog the nozzle and remove the blockage. Can use special dredging tools, such as fine wire, compressed air, etc., will be blocked in the nozzle impurities cleaned out. If the blockage is more serious, the upper flange can be disassembled to completely remove the blockage. Secondly, check the vibrating screen screen cloth, if the screen cloth is broken, it should be replaced in time to avoid the large particles of impurities into the desander, and block the nozzle again. At the same time, adjust the nozzle to increase the liquid throughput and improve the effect of desanding. Start the equipment during the cycle, and observe whether the liquid out of tozzle returhe nns to normal. If the equipment is driven by a diesel engine, the operating parameters of the equipment can be adjusted by reducing the pump speed and the impeller size to avoid high inlet pressure caused by too fast pump speed or too large impeller size. In addition, it is also necessary to check whether the throttle valve position is correct, adjust the valve opening degree to ensure that the liquid can be smoothly discharged through the nozzle .
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