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The cavitation of the mud centrifugal pump in oil drilling refers to the phenomenon that during the oil drilling process, when the local pressure inside the mud centrifugal pump is lower than the saturation vapor pressure of the mud at the current temperature, the water in the mud vaporizes to form bubbles. These bubbles quickly condense and burst when they flow with the mud to the high-pressure area, resulting in a series of harmful effects. Ⅰ. Causes of Cavitation Installation aspects: If the installation height of the pump is too high, the pressure at the pump inlet will decrease. When it is lower than the saturation vapor pressure of the mud, cavitation is likely to occur; if the resistance of the suction pipeline is too large, such as a long and slender pipeline, many bends, a small diameter, or blockage, it will lead to a decrease in the inlet pressure and trigger cavitation. Operation parameter aspects: If the flow rate is too large, exceeding the designed flow rate of the pump, the flow velocity at the impeller inlet will increase, and the pressure will decrease, increasing the possibility of cavitation; if the mud temperature is too high, the saturation vapor pressure of the mud will increase, and it is more likely to reach the saturation vapor pressure and vaporize under the same pressure conditions. Mud property aspects: The properties of the mud, such as density, viscosity, and gas content, affect the occurrence of cavitation. For example, mud with a high gas content is likely to form bubbles inside the pump, increasing the risk of cavitation; too high viscosity will make it difficult for the mud to be sucked in, resulting in a decrease in the inlet pressure. Ⅱ. The cavitation of the mud centrifugal pump can be judged from the following aspects: Sound judgment Noise generation: When cavitation occurs, due to the formation, development, and bursting of bubbles, irregular noise will be generated, and the sound will increase with the aggravation of the cavitation degree. This noise is significantly different from the normal operation sound, and it can be initially judged whether there is cavitation by listening carefully. Abnormal vibration: Cavitation will cause the vibration of the pump body because the impact force generated by the bursting of bubbles will make components such as the impeller and the pump casing subject to uneven forces. By touching the pump body or using a vibration monitoring instrument, it can be found that the vibration amplitude of the pump increases significantly, and the vibration frequency will also change. Compared with the stable state during normal operation, the vibration during cavitation is more intense, and sometimes the entire pump device can even be felt shaking. Performance change judgment Flow rate decrease: Cavitation will cause the fluid flow inside the pump to be obstructed. The bubbles occupy a certain space, reducing the effective flow area of the mud, thus resulting in a decrease in the flow rate. If it is found that the actual flow rate of the pump is significantly lower than the rated flow rate, and other possible causes, such as pipeline blockage and the valve not being fully open, have been excluded, the possibility of cavitation needs to be considered. Head decrease: Cavitation will damage the normal working state of the impeller, reducing the impeller's ability to do work on the mud, and thus leading to a decrease in the head. When the outlet pressure of the pump is significantly lower than the normal operating pressure and the head cannot meet the system requirements, cavitation may be one of the reasons. Efficiency decrease: During the cavitation process, due to the formation and bursting of bubbles, energy will be consumed. At the same time, the flow state of the fluid becomes disordered, resulting in a decrease in the overall efficiency of the pump. If it is found that the energy consumption of the pump increases, but the output flow rate and head do not increase accordingly, or even decrease, it is very likely that cavitation has occurred. Appearance inspection judgment Impeller surface damage: Regularly disassemble the pump for inspection. If there are pits, honeycomb-like depressions, or wear marks on the impeller surface, especially at the inlet and leading edge of the blades, it is likely caused by cavitation. With the development of cavitation, these damages will gradually expand, and in severe cases, it may even lead to the perforation or fracture of the impeller blades. Inner wall damage of the pump casing: When inspecting the inner wall of the pump casing, if there are similar cavitation marks, such as local wear, scratches, or small-area peeling, it also indicates that there may be a cavitation problem with the pump. Especially in the area near the impeller outlet and the volute tongue, due to the large pressure change here, cavitation damage is more likely to occur. In addition, it can also be judged by observing the vacuum gauge installed at the pump inlet and the pressure gauge at the outlet. If the reading of the vacuum gauge increases abnormally, and at the same time, the reading of the pressure gauge decreases abnormally, this may also be a sign of cavitation, because cavitation will lead to a decrease in the pressure at the pump inlet and unstable pressure at the outlet. Ⅲ. Cavitation has a significant impact on the service life of the mud centrifugal pump, mainly reflected in the following aspects: Centrifugal pump impeller damage: When cavitation occurs, the bubbles burst near the impeller surface, and the generated impact force will continuously erode the impeller. In the initial stage, pits will appear on the impeller surface. As cavitation intensifies, the pits gradually expand and connect into honeycomb-like depressions, causing the material on the impeller surface to fall off, resulting in the thinning, perforation, or even fracture of the impeller blades, seriously damaging the structural integrity and hydraulic performance of the impeller, and greatly shortening the service life of the impeller. An impeller that could originally be used for several years may need to be replaced within a few months or even a shorter time due to severe cavitation. Centrifugal pump casing wear: The bubbles generated by cavitation will also burst inside the pump casing, causing impact and erosion on the inner wall of the pump casing, resulting in wear, scratches, and depressions on the inner surface of the pump casing, reducing the strength and wear resistance of the pump casing. Under the long-term effect of cavitation, cracks may appear in the pump casing, affecting its sealing performance and pressure-bearing capacity, and thus shortening the service life of the pump casing, which requires early repair or replacement. Pump shaft failure: The vibration and unstable fluid flow caused by cavitation will make the pump shafts bear additional loads and alternating stresses. This will accelerate the wear of the shafts, leading to an increase in the clearance of the shafts and a decrease in precision, and then triggering faults such as shaft heating and seizure, greatly shortening the service life of the shafts. The original normal service cycle may be several years, but under the influence of cavitation, the bearings may need to be replaced in less than a year. Seal damage: The vibration and pressure fluctuations caused by cavitation will affect the sealing performance of the pump, subjecting the seals to additional impacts and wear. For mechanical seals, it may lead to increased wear and deformation of the sealing surface, losing the sealing effect and causing mud leakage; for packing seals, it will accelerate the wear of the packing, and frequent adjustment and replacement of the packing are required. The damage of the seals not only affects the normal operation of the pump but may also lead to the leakage of the medium, polluting the environment, and increasing the maintenance cost and downtime, indirectly affecting the overall service life of the mud centrifugal pump. In conclusion, cavitation will damage the key components of the mud centrifugal pump from multiple aspects, significantly shortening its service life, increasing the maintenance cost and equipment replacement frequency. Therefore, during the use of the mud centrifugal pump, the cavitation problem must be taken seriously and effective preventive measures should be taken. Ⅳ. In order to reduce the cavitation of the mud centrifugal pump in oil drilling, measures can also be taken from aspects such as optimizing equipment design and selection, improving installation conditions, optimizing operation, and strengthening maintenance management. The specific introductions are as follows: Optimizing design and selection Reasonable pump type selection: According to the characteristics of the oil drilling mud, including parameters such as flow rate, head, density, and viscosity, select a suitable centrifugal pump model. Ensure that the performance curve of the selected pump matches the actual working conditions, so that the pump operates in the high-efficiency area and avoids working under conditions deviating from the designed working conditions to reduce the occurrence of cavitation. Adopting anti-cavitation design: Select impellers with anti-cavitation performance design, such as using double-suction impellers, which can make the flow velocity distribution at the impeller inlet more uniform, reduce the local pressure drop, and reduce the possibility of cavitation. In addition, optimizing the blade shape and the position of the inlet edge of the impeller can also improve the flow situation of the fluid inside the impeller and enhance the anti-cavitation ability of the pump. Improving installation conditions Controlling the installation height: According to the allowable cavitation margin of the pump and the actual on-site situation, accurately calculate the installation height of the pump. The installation height should ensure that the pressure at the pump inlet is higher than the saturation vapor pressure of the mud at the working temperature to prevent the formation of bubbles. Usually, the lower the installation height, the more conducive it is to avoiding cavitation, but the on-site space layout and operation convenience also need to be considered. Optimizing the suction pipeline: Try to shorten the length of the suction pipeline, reduce unnecessary bends, valves, and other pipe fittings to reduce the pipeline resistance. At the same time, select an appropriate pipe diameter to ensure that the flow velocity of the mud in the suction pipeline is moderate, generally, it is recommended that the flow velocity be controlled between 1.5 - 2.5m/s. In addition, ensure the sealing performance of the suction pipeline to prevent air from leaking into the pipeline and avoid cavitation caused by air accumulation. Optimizing operation Stabilizing operation parameters: Keep the operation parameters of the pump, such as flow rate and head, stable, and avoid large fluctuations. Through reasonable adjustment of the outlet valve or the use of variable frequency speed regulation and other methods, make the pump operate near the designed working conditions. Avoid long-term operation under extreme working conditions such as small flow rate and high head or large flow rate and low head to prevent uneven pressure distribution inside the pump and the occurrence of cavitation. Controlling the mud temperature: Too high a mud temperature will increase the saturation vapor pressure of the mud and increase the risk of cavitation. Therefore, effective cooling measures should be taken, such as setting up a mud cooler or using circulating cooling water and other methods to control the mud temperature within a reasonable range, generally, it is recommended that the mud temperature does not exceed 60℃. Reducing the gas content of the mud: Too high a gas content in the mud will promote the occurrence of cavitation. Before the mud enters the pump, a degassing device can be used to pre-treat the mud to reduce its gas content. At the same time, pay attention to avoiding the formation of vortices in the mud tank to prevent air from being drawn into the mud. Strengthening maintenance management Regular inspection and maintenance: Regularly inspect the mud centrifugal pump, including the wear conditions of components such as the impeller, pump casing, and seals, and timely find and replace damaged or severely worn components. Check the pump's bearings, lubrication system, and cooling system, etc., to ensure their normal operation, so as to ensure the overall performance of the pump and reduce the impact of cavitation. Cleaning and maintenance: Keep the pump body and the suction pipeline clean, regularly clean the filter and impurities to prevent blockage and ensure that the mud can flow smoothly into the pump. At the same time, carry out appropriate maintenance on the pump, such as regularly adding lubricating oil and replacing seals, etc., which helps to improve the operation efficiency and reliability of the pump and reduce the probability of cavitation occurrence.    

The mud pump centrifugal super charging pump is an important device in the mud pump system. The following is a detailed introduction to it: Ⅰ. Definition and Function Basic Definition: The mud pump centrifugal super charging pump is usually a small auxiliary pump connected to the suction line of the mud pump. Its main function is to create a vacuum by discharging air and filling the pump with drilling fluid. This pre-fills the mud pump, enabling it to operate efficiently and provides the required pressure for the circulation of the drilling mud. Working Principle: It operates based on the principle of centrifugal force. The impeller rotates at a high speed, generating centrifugal force that causes the drilling mud to move from the center of the impeller to the edge. This movement creates a pressure difference, with low pressure at the impeller inlet and high pressure at the outlet. Therefore, the mud is sucked in from the suction port and discharged from the outlet under pressure, realizing the transportation of the drilling mud. Ⅱ. Main Components Centrifugal Pump Impeller: Semi-closed impellers or closed impellers are usually used. The semi-closed impeller is suitable for transporting mud containing certain particles, which can reduce the wear of the particles on the impeller and has good passageability; the closed impeller can better improve the efficiency and head of the pump and is suitable for occasions with high requirements for mud transportation. Pump Casing: It is generally made of wear-resistant materials, such as high chromium alloy, wear-resistant cast iron, etc., to withstand the erosion and wear of the mud. The shape of the pump casing is designed as a spiral flow channel, allowing the mud to gradually decelerate in the pump casing and convert the kinetic energy into pressure energy to achieve the pressurization of the mud. Shaft Seal: To prevent mud leakage and air from entering the pump, the shaft seal device is crucial. Common shaft seals include mechanical seals and packing seals. Mechanical seals have the advantages of good sealing performance, small leakage, and long service life; packing seals have the characteristics of simple structure, low cost, and convenient maintenance. Bearings: They are used to support the pump shaft and ensure the rotation accuracy and stability of the pump shaft. Since the mud pump centrifugal super charging pump may bear large radial and axial forces during operation, the bearings usually need to have high load-bearing capacity and wear resistance. Ⅲ. Structural Features Wear-resistant Materials: Due to the abrasiveness of the drilling mud, the components of the pump in contact with the mud, such as the impeller and the pump casing, are usually made of wear-resistant materials such as high chromium alloy and wear-resistant ductile iron. This enhances the wear resistance of the pump and prolongs its service life. Grease Lubrication: The bearings of the pump are usually lubricated with grease. This lubrication method can reduce the friction and wear between the bearing and the shaft, ensuring the smooth operation of the pump and is suitable for the working conditions where the pump needs to operate continuously for a long time. Ⅳ. Advantages In terms of Structure and Installation Simple and Compact Structure: The mud pump centrifugal super charging pump is usually composed of main components such as the pump body, impeller, and shaft. The overall structure is relatively simple, without complex transmission devices or multi-chamber structures. Easy Installation: It adopts a pipeline structure design, with the inlet and outlet on the same straight line. During installation, only the inlet and outlet need to be docked. It can be directly installed in series like a pipeline, occupying a small floor space. In terms of Performance and Operation High Efficiency: With an advanced impeller design and optimized internal structure, it can efficiently convert the mechanical energy of the motor into the pressure energy and kinetic energy of the mud, maintaining a high working efficiency under rated working conditions. Stable Operation: The absolute concentricity of the pump shaft and the excellent dynamic and static balance of the impeller ensure that the pump has small vibration and low noise during operation. For example, when the mud pump is running, it will not produce large vibrations and noises, providing a good working environment. Convenient Flow Regulation: The flow is directly proportional to the rotational speed, and the flow can be easily adjusted through a speed change mechanism or a speed-regulating motor, enabling flexible adjustment of the mud transportation volume according to the actual working conditions. Strong Self-priming Ability: Generally, it has a certain self-priming ability. Before starting, there is no need for a large amount of priming operations like some other types of pumps. It can quickly discharge the air in the suction pipe and realize the smooth suction of the mud. In terms of Maintenance and Operation Simple Operation: The operation is relatively simple, and the starting and stopping processes are relatively convenient, without complex operation procedures and professional skills. And it does not require frequent monitoring and adjustment during operation, making it easy to achieve automation and remote operation. Low Maintenance Cost: The simple structure makes the maintenance and repair work relatively easy, and the replacement of parts is also relatively convenient. For example, when replacing the vulnerable parts such as the impeller and seal of the mud pump during maintenance, there is no need to disassemble a large number of parts, reducing the maintenance cost and repair time. Ⅴ. When choosing a suitable model of the mud pump centrifugal super charging pump, multiple factors need to be comprehensively considered. The following are the specific key points:Medium Characteristics Viscosity: High viscosity of the mud will affect the performance and efficiency of the pump, reducing the head and flow of the pump. For mud with a viscosity greater than 500mPa・s, a centrifugal super charging pump with a large passage impeller and low rotational speed is advisable to reduce the flow resistance and prevent blockage. Solids Content: Mud with a high solids content is highly abrasive to the pump. When the sand content is below 15%, a pump made of ordinary cast iron material can be used; when the sand content is between 15% and 40%, wear-resistant materials such as high chromium alloy are required; when the sand content exceeds 40%, a pump made of duplex stainless steel or with a tungsten carbide coating on the surface should be considered. Corrosiveness: If the mud is corrosive, such as containing acids, alkalis, and other chemical substances, a pump made of corrosion-resistant materials, such as rubber-lined, plastic-lined, titanium alloy, etc., should be selected to extend the service life of the pump. Flow and Head Requirements Flow: Determine the required mud transportation flow according to the actual engineering needs, generally in cubic meters per hour (m³/h). For example, in large-scale mining operations, a flow of hundreds of cubic meters per hour may be required. The rated flow of the selected pump should be slightly larger than the actual required flow to ensure that the transportation requirements can be met under different working conditions. Head: The head refers to the height that the pump can lift the mud, in meters (m). The required head needs to be calculated according to factors such as the transportation distance, height difference, and pipeline resistance. For example, when transporting mud from the underground to the ground, if the vertical height is 100 meters, and considering the pipeline friction and other losses, a pump with a head of 120-150 meters may need to be selected. Working Environment Space Limitation: If the installation space is limited, such as in some underground operations or small sewage treatment plants, a vertical mud pump centrifugal super charging pump can be selected, which occupies a small floor space; in an open space, such as the open-air operation area of a large mine, a horizontal pump is more convenient for installation and maintenance. Temperature and Humidity: In a high-temperature environment, the materials and seals of the pump need to have high-temperature resistance; in a humid or corrosive gas environment, the moisture-proof and anti-corrosion performance of the electrical equipment of the pump should be considered. Power and Control Power Source: There are power-driven and diesel-driven methods. Power-driven is suitable for places with a stable power grid power supply, with the advantages of low operating cost and high efficiency; diesel-driven is suitable for field or remote areas without power grid coverage, such as field geological exploration operations. Control Mode: Select a pump with manual control, automatic control, or remote control according to actual needs. Automatic control and remote control can realize real-time monitoring and adjustment of the operating status of the pump, improving work efficiency and automation level, and are suitable for large-scale engineering projects or unattended places. Other Factors Maintenance Cost: It includes the replacement cost of vulnerable parts, the difficulty of maintenance, etc. Selecting a pump with a simple structure and strong universality of vulnerable parts can reduce the maintenance cost and difficulty, shorten the maintenance time, and improve the operating efficiency of the equipment. Ⅵ. Maintenance of the Mud Pump Centrifugal Charging Pump 1.Daily Maintenance The maintenance and upkeep of the mud pump centrifugal super charging pump involve multiple aspects such as daily inspection, regular maintenance, and key component maintenance. The following are the specific methods and key points: Operation Status Monitoring Pressure and Flow: Closely monitor the inlet and outlet pressure and flow of the pump to ensure that they operate stably within the rated parameter range. Abnormal fluctuations in pressure or flow may indicate problems such as blockage, leakage, or component damage inside the pump. Temperature and Vibration: Check the temperature of the pump body, bearings, and motor to prevent overheating. Generally, the bearing temperature should not exceed 70℃, and the motor temperature should not exceed the value specified on the nameplate. At the same time, pay attention to the vibration situation during the operation of the pump. Abnormal vibration may indicate that the pump shaft is misaligned, the impeller is unbalanced, or the foundation is loose. Sound: A normally operating pump has a stable and uniform sound. If abnormal noises, such as friction sounds, impact sounds, or cavitation sounds, occur, stop the machine immediately for inspection to determine whether there are component wear, looseness, or cavitation phenomena. Appearance Inspection Leakage Situation: Check whether there is mud leakage at the pump body, pipeline connection parts, and seals. Slight leakage may be due to wear or improper installation of the seals, and severe leakage may lead to a decrease in the pump's performance or even damage, which needs to be dealt with in a timely manner. Component Integrity: Check the appearance of the pump to ensure that all components are undamaged, not loose, and the protective devices are complete and effective. If the bolts are found to be loose, tighten them in a timely manner; if there are cracks or damage to the casing, evaluate the impact on the pump's performance and repair or replace it in a timely manner. 2.Regular Maintenance Cleaning and Lubrication Cleaning: Regularly clean the mud, dust, and oil stains on the surface of the pump body to prevent their accumulation from affecting heat dissipation and corroding the pump body. For the suction strainer, clean it frequently to avoid insufficient suction flow caused by strainer blockage, which may lead to problems such as cavitation. Lubrication: According to the requirements of the equipment manual, regularly add or replace the lubricating oil for the rotating parts such as the bearings. Generally, for bearings lubricated with lubricating oil, the lubricating oil should be replaced every 2000-3000 hours of operation; for bearings lubricated with lubricating grease, the lubricating grease should be replenished every 1000-1500 hours of operation. Performance Testing and Adjustment Performance Testing: Test the performance of the pump, including parameters such as flow, head, and efficiency, at regular intervals (such as every 3-6 months), and compare them with the original performance data to evaluate the performance changes of the pump. If the performance drops significantly, analyze the reasons and carry out maintenance and adjustment. Adjustment: Make necessary adjustments to the pump according to the performance test results. For example, by adjusting the clearance between the impeller and the pump casing, the performance of the pump can be improved; for pumps using variable frequency speed regulation, adjust the motor frequency according to actual needs to optimize the operating conditions of the pump. 3.Key Component Maintenance Impeller and Pump Casing Wear Inspection: Regularly check the wear situation of the impeller and the pump casing, especially the blades of the impeller and the flow channel parts of the pump casing. If the wear of the impeller exceeds the specified limit, it will lead to a decrease in the flow and head of the pump, and it needs to be replaced in a timely manner. For the situation of slight wear, repair technologies such as wear-resistant coatings can be adopted. Corrosion Treatment: If the medium is corrosive, pay attention to the corrosion situation of the impeller and the pump casing. When signs of corrosion are found, measures such as anti-corrosion coatings and replacement of corrosion-resistant materials can be taken. Sealing Device Mechanical Seal: Check the wear situation of the mechanical seal and observe whether there are scratches, cracks, or deformations on the sealing surface. Generally, the service life of the mechanical seal is 8000-12000 hours. When the service life is reached or problems such as leakage occur, it should be replaced in a timely manner. At the same time, ensure that the flushing fluid system of the mechanical seal operates normally to ensure the cooling and lubrication of the sealing surface. Packing Seal: Regularly check the wear and aging situation of the packing, and adjust the tightness of the packing gland in a timely manner to ensure the sealing effect. When the leakage amount of the packing is too large, the packing should be replaced.