Chemical melt metering pump

Chemical Melt Metering Pump is a widely used equipment in the chemical industry, and here is a detailed introduction to it:

I. Definition and Working Principle

Definition: A melt metering pump is a positive displacement conveying device whose flow rate is strictly proportional to the pump's rotational speed. It is primarily used for conveying, pressurizing, and metering high-temperature, high-viscosity polymer melts.

Working Principle: The working principle of a melt metering pump mainly relies on the rotational motion of its internal gears and their intermeshing. Molten material enters the pump body through the inlet, and the gear shaft begins to rotate (typically powered by a motor). During gear rotation, the intermeshing of the driving and driven gears causes changes in the working volume, thereby pushing the melt. As the gears rotate, the melt is brought into the conveying area from both sides, and the re-engagement of the gears squeezes the melt in the tooth spaces and presses it into the outlet piping.

II. Application Areas

Melt metering pumps have a wide range of applications in the chemical industry, particularly in the extrusion molding of plastics, resins, rubbers, and chemical fiber products, such as granulation, films, pipes, sheets, plates, artificial fibers, optical fibers, medical plastic catheters, and other industries. Additionally, they can be used in melt-blown fabrics, non-woven fabrics, optical fiber cables, plastic processing, adhesive production, precision extrusion, and other fields.

III. Main Characteristics

Precise Conveying: The melt metering pump can precisely control and convey molten material, ensuring stability in flow rate and pressure, which is crucial for applications requiring precision processing or accurate ratio mixing.

Pressure Balancing: It provides stable pressure in the piping, helping to balance the flow of molten material, maintaining a uniform extrusion or injection process, and avoiding the generation of air or bubbles.

Stable Flow Rate: Through the design of its gears, it can effectively isolate the influence of pressure fluctuations and flow rate fluctuations in the feed area on the discharge area, achieving stable flow rate conveying.

Reduction of Bubbles and Defects: Providing stable pressure and flow rate reduces or eliminates bubbles, voids, or defects in the molten material, which is essential for manufacturing high-quality products.

Control of Molten Material Temperature: Combined with a heating system, it effectively controls the temperature of the molten material, which is important for certain applications.

Cost Reduction: It reduces losses of the melt during conveyance, saves energy consumption, and improves production efficiency.

Increased Production: By pressurizing, stabilizing pressure, and controlling pressure fluctuations, it can increase production output and energy efficiency.

IV. Selection and Installation Considerations

Selection:

Consider the properties of the conveyed material, such as viscosity, particle size and impurities, corrosion, toxicity, and temperature stability.

Choose the pump type and specification based on the flow rate and pressure required by the process.

Consider equipment investment and maintenance costs, selecting a pump with high cost-effectiveness.

Consider the convenience of operation and maintenance during selection.

Installation:

Ensure the concentricity of the pump base and motor drive shaft before installation to avoid shaft breakage and pump damage.

The installation base should be flat and sturdy to ensure stable pump operation.

Tighten the bolts evenly to avoid excessive local stress.

The installation error of the universal coupling should be controlled within the allowable range.

V. Maintenance and Servicing

To ensure the safe and stable operation of the melt metering pump and extend its service life, regular maintenance and servicing should be performed. This includes checking and adjusting the position of the gland, ensuring that the cooling water connection is installed correctly and connected to a water source (for pumps using spiral seals), and regularly cleaning the shaft seal. Meanwhile, it is necessary to follow the operating manual and maintenance guide provided by the manufacturer for correct operation and maintenance.

In summary, chemical melt metering pumps play an important role in the chemical industry. Their characteristics of precise conveying, pressure balancing, and stable flow rate make them an ideal choice for conveying, pressurizing, and metering high-temperature, high-viscosity polymer melts. Various factors should be fully considered during selection, installation, use, and maintenance to ensure that the pump's performance and efficiency are fully utilized.

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