Overview
The small-flow coal slurry transfer pump is a device used to transport coal slurry. It can transfer coal slurry from one location to another under conditions of relatively low flow. It plays an important role in industries such as coal processing and coal chemical engineering, especially in some technological processes where the flow requirement is not high but certain requirements for transportation accuracy and stability exist.
Working Principle
Centrifugal Type:
The centrifugal coal slurry transfer pump mainly relies on the centrifugal force generated by the rotation of the impeller to transport coal slurry. When the impeller rotates at a high speed, the coal slurry makes a circular motion under the drive of the impeller. Under the action of centrifugal force, the coal slurry is thrown from the center of the impeller to the edge of the impeller and then discharged through the outlet of the pump body. Meanwhile, a low-pressure area is formed at the center of the impeller, and new coal slurry is continuously sucked into the center of the impeller under the action of external pressure, thus realizing a continuous transportation process. The flow and head (pressure) of this type of pump can be controlled by adjusting the rotation speed of the impeller, and it is suitable for coal slurry with a certain degree of fluidity.
Positive Displacement Type:
Taking the piston type as an example, the piston makes a reciprocating motion in the pump cylinder. When the piston moves backward (away from the outlet direction), a negative pressure is formed in the pump cylinder, and the coal slurry enters the pump cylinder through the inlet valve under the action of external atmospheric pressure. When the piston moves forward, the inlet valve closes and the outlet valve opens, and the coal slurry is pushed by the piston to be discharged through the outlet valve out of the pump cylinder. By precisely controlling the movement frequency and stroke of the piston, accurate transportation of small-flow coal slurry can be achieved. The characteristic of this type of pump is that the flow is relatively stable and is less affected by changes in the outlet pressure.
Main Structural Components
Pump Body:
The pump body is the outer shell that houses key components such as the impeller (for the centrifugal type) or the piston (for the positive displacement type). Its internal structure design will vary according to the working principle of the pump. For the centrifugal pump body, there are flow channels inside to guide the coal slurry to enter from the center of the impeller and then be discharged from the edge; for the positive displacement pump body, there is a cylinder body that cooperates with the piston inside, and there are precise inlet and outlet channels and valve installation positions. The pump body is usually made of wear-resistant and corrosion-resistant materials because coal slurry has a certain degree of corrosiveness and abrasiveness, such as high chromium alloy cast iron and other materials.
Impeller / Piston:
The impeller (for the centrifugal type) is the core component of the centrifugal pump, and its shape and size directly affect the performance of the pump. The impeller generally has multiple blades and transfers energy to the coal slurry through high-speed rotation. The piston (for the positive displacement type) needs to have good sealing performance, and its surface usually has a wear-resistant coating to prevent the solid particles in the coal slurry from wearing the piston, and the dimensional accuracy of the piston is required to be relatively high to ensure the accuracy of the displacement of each reciprocating motion.
Sealing Device:
Since coal slurry must not leak, the sealing device is of crucial importance. Common sealing methods include mechanical sealing and packing sealing. Mechanical sealing prevents coal slurry leakage by the close fitting of the stationary and rotating rings. It has a good sealing effect but is relatively costly and has higher requirements for installation and maintenance. Packing sealing utilizes packing (such as graphite packing, etc.) to fill the gap between the shaft and the pump body, and the sealing is achieved by compressing the packing. This sealing method is relatively simple but requires regular maintenance, such as adding or replacing the packing.
Inlet and Outlet Valves (for the Positive Displacement Type):
For the positive displacement pump, the inlet and outlet valves control the entry and exit of coal slurry. The opening and closing times and sealing performance of the valves directly affect the flow and efficiency of the pump. Generally, ball valves or globe valves are used. These valves need to be able to withstand the scouring and wearing of coal slurry and have good sealing performance. The material of the valves is usually also a wear-resistant and corrosion-resistant metal material.
Performance Characteristics
Flow Characteristics:
The flow range of the small-flow coal slurry transfer pump is generally below several cubic meters per hour, and the flow accuracy is relatively high. For example, the flow of some small positive displacement coal slurry transfer pumps can be precisely controlled within the range of 0.1 - 1 cubic meter per hour, which can meet the requirements of occasions where the coal slurry transportation volume needs to be precisely controlled, such as small coal chemical engineering experimental devices or fine coal processing processes.
Pressure Characteristics:
It can generate a certain transportation pressure to overcome factors such as pipeline resistance and height difference. The head (pressure) of the centrifugal pump is related to the rotation speed of the impeller and can generally reach a head of several tens of meters; the pressure of the positive displacement pump mainly depends on the thrust of the piston and the strength of the pump body. Some piston-type coal slurry transfer pumps can provide a relatively high pressure, which is suitable for situations where coal slurry needs to be transported to a higher position or over a long distance.
Adaptability:
It can adapt to different properties of coal slurry. Factors such as the viscosity, particle size, and concentration of coal slurry will affect the performance of the pump. The small-flow coal slurry transfer pump can adjust its own working parameters (such as the rotation speed of the impeller for the centrifugal pump, the movement frequency of the piston for the positive displacement pump, etc.) to adapt to different properties of coal slurry. For example, for coal slurry with a relatively high viscosity, the positive displacement pump may show better adaptability because its transportation principle has a relatively small relationship with the fluidity of coal slurry.
Application Scenarios
Coal Chemical Engineering Laboratory:
In the laboratory research of coal chemical engineering, it is necessary to accurately transport a small amount of coal slurry for experimental analysis. The small-flow coal slurry transfer pump can accurately transport the coal slurry to experimental reactors, analytical instruments, and other equipment, providing a stable coal slurry supply for the experiment. For example, in the hydrogenation reaction experiment of coal slurry, it is necessary to transport a quantified amount of coal slurry into a high-pressure reactor, and the small-flow coal slurry transfer pump can meet this requirement of accurate transportation.
Small Coal Processing Plants:
In some small coal processing enterprises, the demand for the transportation volume of coal slurry is not large. For example, in the coal washing and sorting process, a small amount of coal slurry is transported from one washing and sorting stage to another stage, or the coal slurry is transported to a small storage tank. The small-flow coal slurry transfer pump can well complete this transportation task, and its relatively small occupied area and low energy consumption also meet the requirements of small enterprises.
