Top Slurry Pumps: Things You May Want to Know
The top slurry pumps, as a key profit-maker in Shijiazhuang Minerals Equipment Co., Ltd., is always recognized for high cost-performance ratio and specific application. 'These are reasons for its good sales here,' is a comment made by our purchaser. This can be attributed to the design, manufacturing, and quality control mainly. At the very beginning, we carried out a lot of market research and analyzed the consumers' demands. This is the basis for the design which was then proven to be a perfect combination of aesthetics and functions. The manufacturing is standardized and traceable. This guarantees the product quality from the source. The final inspection is also very important, making the product 100% assured.
The influence of CNSME PUMP branded products in the international market is growing. These products are manufactured in line with world-class specifications and are known for their superior quality. These products gain a high market share, capturing customers' eyes with superior performance, long service life and reasonable price. Its constant innovation, improvement and potentially broad application prospects have won the reputation in the industry.
At CNSME, customers can get top slurry pumps and other products together with more considerate services. We have upgraded our distribution system, which enables a faster and safer delivery. Besides, to better cater to customer's actual need, the MOQ of the customized products is negotiable.
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1. The cavitation phenomenon of the pump:
When the liquid is at a certain temperature and the pressure is reduced to the vaporization pressure at that temperature, the liquid will produce bubbles. This phenomenon of generating bubbles is called cavitation. When the bubbles generated during cavitation flow to a high pressure place, their volume decreases so that they burst. This phenomenon of bubbles disappearing in a liquid due to pressure rise is called cavitation collapse.
When the pump is in operation, if the absolute pressure of the pumped liquid is reduced to the vaporization pressure of the liquid at the current temperature in the local area of the flow-through part (usually somewhere behind the inlet of the impeller blade) for some reason, the liquid will be here. When the liquid containing a large number of bubbles passes through the high-pressure zone in the impeller, the high-pressure liquid around the bubbles will cause the bubbles to shrink sharply and burst. While the bubbles condense and burst, the liquid particles fill the voids at a high speed, and at this moment a strong water hammer effect is generated, and the metal surface is hit at a high punching frequency, and the impact stress can reach hundreds to thousands Atmospheric pressure will break down the wall thickness in severe cases.
The process of generating air bubbles and bursting of air bubbles in the water pump to damage the flow-through part is the cavitation process in the water pump. After the pump cavitation occurs, in addition to damaging the flow-passing parts, it will also generate vibration and noise, and cause the original performance of the pump to decline. In severe cases, the liquid in the pump will be interrupted and cannot work normally.
Second, the basic relationship between pump cavitation
The conditions for pump cavitation are determined by the pump itself and the suction device. Therefore, to study the conditions of cavitation, both the pump itself and the suction device should be considered. The basic relationship of the pump is:NPSHc≤NPSHr≤[NPSH]≤NPSHa
NPSHa=NPSH(NPSHc)－－－－－－－－—The pump starts cavitation
NPSHa＞NPSHr（NPSHc）－－－－－－The pump has no cavitation
In the formula, NPSHa - the NPSH of the device is also called the effective NPSH, the larger the NPSH, the less likely it is to erode;
NPSHr———Pump NPSH, also known as necessary NPSH or pump inlet pressure drop, the smaller the better the anti-cavitation performance;
NPSHc————critical NPSH, which refers to the NPSH corresponding to a certain value of pump performance decline;
[NPSH]－－－－Permissible NPSH is used to determine the operating conditions of the pump, usually [NPSH]=(1.1～1.5)NPSHc.
3. Measures to prevent cavitation:
In order to prevent cavitation, NPSHa must be increased to make NPSHa>NPSHr. The measures to prevent cavitation are as follows:
1. Reduce the geometric suction height hg (or increase the geometric backflow height);
2. To reduce the suction loss hc, try to increase the diameter of the pipe, and minimize the length of the pipe, elbows and accessories;
3. Prevent working under large flow for a long time;
4. Under the same speed and flow rate, the double suction pump is adopted, and the pump is not prone to cavitation due to the reduced inlet flow rate;
5. When cavitation occurs in the pump, the flow should be reduced as much as possible to reduce the power and speed;
6. The condition of the pump suction pool has an important impact on pump cavitation;
7. For pumps operating under harsh conditions, in order to avoid cavitation damage, cavitation-resistant materials can be used.
The impeller is a critical slurry pump component, directly influencing key performance factors such as efficiency, flow rate, head, and wear resistance. The most common types of slurry pump impellers include the open impeller, semi-open impeller, and closed impeller. Each type has distinct structural characteristics and is suited to different application scenarios:
Open Impeller
Structural Characteristics: The open impeller has no side covers, with only the blades and the supporting hub exposed. The front and rear of the blades are open, allowing solid particles to pass through the impeller more easily.
Function and Application: Open impellers are typically used for handling slurries containing larger particles or fibrous materials. Their simple design makes them easy to clean, making them particularly suitable for conditions that require frequent maintenance. Although the efficiency of an open impeller is relatively low, it performs well when dealing with high solid content and easily clogged slurries.
Semi-Open Impeller
Structural Characteristics: The semi-open impeller features a back cover, but the front remains open. This partially enclosed design allows for better control of fluid flow while still maintaining some anti-clogging capabilities.
Function and Application: Semi-open impellers are ideal for handling slurries with medium-sized particles, combining the advantages of both open and closed impellers. They offer good efficiency and wear resistance, making them suitable for applications that balance and anti-clogging performance.
Closed Impeller
Structural Characteristics: The closed impeller is fully enclosed by front and rear covers, creating a complete chamber around the blades. This design allows for better fluid control as it passes through the impeller, resulting in smoother flow and higher pump efficiency.
Function and Application: Closed impellers are mainly used for handling slurries with fewer or smaller solid particles, suitable for conditions requiring high efficiency and high head. While closed impellers may face clogging issues when dealing with high solid content, they perform exceptionally well with clean or lightly contaminated media.
Open Impeller
Structural Characteristics: The open impeller has no side covers, with only the blades and the supporting hub exposed. The front and rear of the blades are open, allowing solid particles to pass through the impeller more easily.
Function and Application: Open impellers are typically used for handling slurries containing larger particles or fibrous materials. Their simple design makes them easy to clean, making them particularly suitable for conditions that require frequent maintenance. Although the efficiency of an open impeller is relatively low, it performs well when dealing with high solid content and easily clogged slurries.
Semi-Open Impeller
Structural Characteristics: The semi-open impeller features a back cover, but the front remains open. This partially enclosed design allows for better control of fluid flow while still maintaining some anti-clogging capabilities.
Function and Application: Semi-open impellers are ideal for handling slurries with medium-sized particles, combining the advantages of both open and closed impellers. They offer good efficiency and wear resistance, making them suitable for applications that balance and anti-clogging performance.
Closed Impeller
Structural Characteristics: The closed impeller is fully enclosed by front and rear covers, creating a complete chamber around the blades. This design allows for better fluid control as it passes through the impeller, resulting in smoother flow and higher pump efficiency.
Function and Application: Closed impellers are mainly used for handling slurries with fewer or smaller solid particles, suitable for conditions requiring high efficiency and high head. While closed impellers may face clogging issues when dealing with high solid content, they perform exceptionally well with clean or lightly contaminated media.
1.Installing (pump, torsigraph,electric motor,pipeline etc)2.Start and venting (1) Pressure transmitter venting(2) Pipeline venting3. Start testing(1)starting from “0” flow rate to the required duty point (flowrate,head),then exceed one or two duty points. (2) collecting successively and cumulatively,total about 10 duty points.4. Issuing test report.
(1) Outlet valve regulation is currently the most commonly used and popular method. A regulating valve is installed on the discharge pipeline of the slurry pump, and the flow rate is adjusted by changing the valve opening. This method is simple and reliable, but it results in significant power loss and poor economic efficiency. It is also ineffective for regulating small or very small flow rates.
(2) Speed regulation, which adjusts flow by changing the rotational speed of the slurry pump impeller. This method has minimal additional power loss and is the most economical approach. However, it requires additional speed-changing mechanisms and motors, resulting in higher initial investment costs. Constant-pressure variable-frequency water supply systems and central air conditioning cooling water circulation systems are two typical examples of variable-frequency speed regulation applied to slurry pump regulation. The method of changing the speed is most suitable for slurry pumps driven by steam turbines, internal combustion engines, and DC motors. Variable frequency regulation can also be used to change the motor speed, and sometimes the speed can be regulated through a hydraulic coupler.
(3) Bypass regulation: This method uses a bypass to divert flow and regulate it, addressing the issue of continuous operation at low flow rates for slurry pumps. However, this results in additional losses due to the diverted flow not being fully utilized, and the process piping also increases accordingly.
(4) Cutting the impeller outer diameter: Adjusting the slurry pump flow rate by cutting the impeller outer diameter results in minimal power loss. However, once the impeller is cut, it cannot be restored, meaning flow rate adjustment is only possible toward lower flow rates. Additionally, the amount of impeller cutting is limited, resulting in a limited flow rate adjustment range. This method is suitable for applications requiring long-term operation at relatively low flow rates with minimal flow rate changes.
(5) Replacing the impeller of the slurry pump: Replacing the impeller with one of a different diameter or outlet width to adjust the flow rate of the slurry pump results in minimal power loss. However, multiple impellers of different diameters must be stocked, and the range of flow rate adjustment is limited.
(6) Blocking part of the impeller flow channel: Reducing the flow rate of the slurry pump by blocking part of the impeller flow channel is equivalent to throttling regulation via an outlet valve. However, this is an active regulation method that reduces additional energy loss, making it more energy-efficient than throttling regulation via a control valve.
(7) Adjust the outlet angle of the blades. Adjusting the outlet angle of the impeller blades to regulate the flow rate of the slurry pump. This method is commonly used in axial flow slurry pumps.
(8) Cavitation regulation. By altering the inlet pressure of the slurry pump to induce cavitation, the characteristic curve of the slurry pump is modified, thereby adjusting its flow rate. Practice has shown that if cavitation regulation is used appropriately, it does not cause severe damage to the flow passage of the slurry pump; on the other hand, it can automatically regulate the flow rate and reduce the power consumption of the slurry pump.
(9) Increasing or decreasing the number of slurry pumps: This method involves adjusting the flow rate of the slurry pump by increasing or decreasing the number of operating slurry pumps, combined with an appropriate merging method.
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Contact: Ms.Serena Zhang
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