In many industries such as oil extraction, mining, building construction and sewage treatment, mud pumps play an irreplaceable key role in ensuring the smooth operation of the entire engineering process. Accurate and scientific selection of mud pump parts is to ensure stable operation of the equipment, improve operational efficiency, cost control and practice environmental protection requirements of the top priority, is the application of mud pumps in various industries must overcome the key links.
一.Key Factors in Selecting Mud Pump Parts
1.Slurry characterisation
(1)Concentration and particle content
The concentration of the slurry and the amount of particles contained in the slurry pump has a significant impact on the operation of the slurry pump. In the high concentration of mud conditions, meaning that the number of solid particles per unit volume increased significantly, which makes the mud flow significantly worse, the difficulty of pumping straight up. At this time, the pump needs to overcome greater resistance when pushing the mud flow, as vehicles in the mud on the road, which requires mud pumps have a stronger power output and more efficient energy conversion capacity to ensure that the mud can be sustained, stable to be transported.
When selecting mud pump parts, the material of the overflow parts should give priority to high hardness, high wear resistance alloy materials, such as high chrome alloy. With its excellent hardness and wear resistance, high chrome alloy can effectively resist the erosion of particles and extend the service life of the parts. At the same time, for the design of the impeller, you can appropriately increase the thickness of the blade, optimise the shape of the blade, and use anti-wear coating technology to further enhance the wear resistance and impact resistance of the impeller, to ensure that the pump’s performance is still reliable in the high-concentration, multi-particle slurry environment.
(2)pH and corrosiveness
Some industries use slurry with strong acidity and alkalinity, showing obvious corrosiveness. For example, in the chemical production of acidic wastewater treatment, acidic wastewater discharge from mines and some special metal mining process of alkaline slurry conveying links, slurry pumps for a long time immersed in such a corrosive medium, facing serious corrosion risks. Strongly acidic or alkaline slurry will react chemically with the pump body, impeller, seals and other metal parts, and gradually erode the surface of the parts, so that the wall thickness of the parts is thinned and the strength of the parts is reduced.
For parts in contact with corrosive mud, the choice of material is crucial. When faced with acidic slurry, stainless steel 316L, Hastelloy and other materials show good acid resistance, which can form a dense passivation film in acidic environments, preventing the acid from further eroding the metal matrix. In alkaline environments, nickel-based alloys have excellent resistance to alkali corrosion, which effectively protects the structural integrity of parts. In addition, the material of the seals also need to be carefully selected, Viton, PTFE and other materials with excellent chemical stability, can maintain good sealing performance in acid and alkali environments, to prevent the leakage of slurry, to ensure the safe and stable operation of the pump.
(3)Temperature and viscosity
Temperature change of mud has a direct and significant influence on its viscosity, which in turn affects the working efficiency of mud pump. In the downhole operation of oil extraction, with the increase of drilling depth, the temperature of the stratum gradually rises, and the temperature of the mud also rises. When the temperature rises, the thermal movement between mud molecules increases, cohesion decreases, resulting in lower viscosity and increased fluidity. It seems to be favourable to pumping, but in fact, the high temperature may trigger the evaporation of water and gas precipitation in the mud, which will cause cavitation and damage to the impeller and other parts of the mud.
On the contrary, in some low-temperature environment of engineering operations, such as winter mine tailings transport, construction of piling in the northern region, the mud temperature is too low, the viscosity increases dramatically, the fluidity deteriorates, the pumping resistance increases dramatically. This requires the mud pump to have a stronger power to overcome the resistance, at the same time, in order to prevent the mud from freezing at low temperatures, affecting the normal startup and operation of the pump, but also need to be equipped with the appropriate heating or insulation device.
From the perspective of parts fit, for high temperature environment, the pump body can be used for high temperature alloy steel, to ensure that the structural strength is not affected by high temperature; impeller, shaft and other key components with a small coefficient of thermal expansion of the material, to prevent thermal expansion and contraction resulting in a decline in fit precision. For low-temperature and high-viscosity conditions, large-diameter inlet pipe can be selected to reduce the mud flow rate and flow resistance; the impeller adopts a special streamlined design to optimise the mud flow path and improve the pumping efficiency. In addition, it can also be considered to add a mixing device at the inlet end of the pump, pre-mixing of high viscosity mud, so that it is uniformly mixed to reduce viscosity and facilitate pumping.
二.Important factors in component selection
1.Pump body and impeller
(1)Material selection
The pump body and impeller, as the core flow parts of the mud pump, are directly subject to the scouring, abrasion and corrosion of the mud, and the suitability of their materials is of utmost importance. In general construction engineering pile foundation construction, small mine tailings initial transport and other conditions, if the slurry concentration is relatively low, fine particles and pH is close to neutral, ordinary cast iron pump body and impeller can meet the basic needs.
However, when faced with demanding, harsh conditions such as oil mining, chemical slurry transport, stainless steel shows excellent performance advantages. In the oil drilling process, downhole mud not only contains high hardness rock particles, may also be mixed with corrosive stratum fluids, at this time, stainless steel pump body and impeller with excellent corrosion resistance, to resist the erosion of various chemicals in the mud, to ensure that the components of the structural integrity of the long term stable operation. Its high hardness and wear-resistant performance can also effectively cope with the high-speed scouring of rock particles, reduce wear and tear, prolong service life, and reduce the downtime and cost loss caused by frequent replacement of parts.
For extreme working conditions, such as acidic wastewater treatment in mines and transport of highly concentrated metal slurries, the alloy material becomes an excellent choice. High-chromium alloy contains a large amount of chromium, can form a dense and tough oxide film on the surface, this oxide film is like a solid ‘shield’, effectively blocking acid, alkali and high hardness ore particles of the invasion, and greatly enhance the wear and corrosion resistance of the pump body and the impeller, to ensure that the slurry pumps run reliably in harsh environments, and provide solid support for the continued advancement of critical industrial processes. It provides solid support for the continuous promotion of key industrial processes.
(2)Structural design
The traditional snail shell flow channel adopts a gradual expansion design according to the principle of fluid dynamics, which can make the mud flow through the flow channel, the flow rate is reduced smoothly, and the kinetic energy is converted into static pressure energy with high efficiency, which reduces the energy loss and improves the pumping efficiency. In terms of impeller structure, closed impeller with precision design of blades and wheel cover, in the fine chemical industry, food processing and other industries, which have strict requirements on flow rate and head control accuracy, the closed impeller is able to accurately transport slurry to ensure stable and efficient production process. Semi-open impellers, on the other hand, enhance the adaptability to slurries containing a small amount of impurities while retaining a certain degree of energy conversion capacity. In scenarios such as secondary recovery of mine tailings and drainage of small construction sites, semi-open impellers allow particles of a certain size to pass through smoothly, preventing impurities from clogging the flow channel and ensuring that pumping operations continue. With its simple and open structure, the open impeller shows superb flow capacity and is fearless of large solid impurities. Under heavy load conditions such as coarse slurry conveying in large-scale mining and high sand content slurry extraction in river dredging, the open impeller can operate efficiently and stably to ensure the smooth progress of the project.
2.Shaft material and strength
As a key component of mud pump to transmit torque and drive the impeller to rotate, the shaft needs to withstand huge torsion force, radial force and vibration load caused by impeller imbalance, mud impact and other factors. In the high strength, long time continuous operation conditions, it is suitable for the selection of high-strength alloy steel shaft.Surface treatment process is also indispensable for shaft performance improvement. Common nitriding treatment can form a layer of nitriding layer on the surface of the shaft with extremely high hardness, strong wear resistance and certain corrosion resistance. This nitrided layer effectively reduces the wear rate and extends the service life of the shaft when it comes into contact with the slurry and seals.
3.Valve Types and Features
The core function of the check valve is to ensure unidirectional flow of slurry, effectively preventing slurry backflow during shutdown or pressure fluctuations. The common swing check valve, relying on the gravity of the valve flap and the impact of the media flow automatically open and close. In the oil pipeline network mud pump outlet, when the pump is running normally, high-pressure mud flap, smooth flow to the pipeline network; once the pump accidentally shut down, the valve flap under the action of gravity quickly fall back to close, to prevent the pipeline network in the mud backflow back to the pump cavity, to avoid damage to the pump impeller reversal, the pump internal parts of the impact, to ensure that the whole transport system is safe and stable for the continuous and reliable delivery of oil to provide a solid guarantee.
The safety valve is like the ‘safety guard’ of the mud pump system, always guarding the system from the threat of overpressure. In the chemical production of high-pressure slurry reactor supporting slurry pump system, if the process flow is abnormal, resulting in a sharp rise in pump outlet pressure, beyond the safety valve set the starting pressure, the safety valve quickly open, part of the slurry discharge to the safe area, reduce the system pressure in a timely manner, to prevent the pump body, pipeline rupture due to overpressure triggering serious leakage, explosion accidents, to ensure the safety of personnel life and the integrity of the production facilities. For the safe operation of chemical production.
Regulating valve is to achieve slurry flow, pressure regulation and control of precision ‘intelligent housekeeper’. In the sludge transfer pump system of urban sewage treatment plant, facing the dynamic demand for sludge flow and pressure at different times and in different treatment processes, the regulating valve precisely adjusts the valve opening according to the instruction of the control system by means of electric, pneumatic or hydraulic actuators. Such as in the sludge dewatering process, need to increase the sludge conveying pressure, the control valve automatically close the throttle area, increase pressure; in the sludge storage tank feeding, increase the opening, smooth flow control, to ensure that the entire sewage treatment process is efficient and orderly operation, improve the quality and efficiency of sewage treatment.
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