Introduction to Forced Circulation Pumps
The forced circulation pump operates using the horizontal thrust along the pump shaft generated by the impeller rotation, hence also known as a horizontal axial flow pump. It is primarily used in industries such as membrane process caustic soda, phosphoric acid, vacuum salt production, lactic acid, calcium lactate, aluminum oxide, titanium dioxide, calcium chloride, ammonium chloride, sodium chlorate, sugar production, molten salt, papermaking, and wastewater for evaporation, concentration, and cooling purposes. It is used to enhance equipment production capacity and increase the heat transfer coefficient of heat exchangers. Therefore, it can also be referred to as an axial flow evaporative circulation pump.
Structural Features of the Forced Recirculation Pump
1. The forced circulation pump operates at a low speed, typically not exceeding 980 rpm, ensuring stable operation in accordance with the crystallization process requirements.
2. Excellent hydraulic performance, efficiency > 70% zone width, good anti-cavitation capability.
3. The pump medium flows vertically downward and horizontally outward. The significant impact of water flow on the pump shaft led to the addition of a shaft sleeve protection device within the pump body. This transfers the media's plunging force to the pump body, ensuring stable operation of the pump and greatly reducing the impact of the medium on the mechanical seal, thereby extending the seal's lifespan. This structural improvement represents a significant step forward in domestic similar products. Additionally, the pump body is made of a monolithic casting for excellent rigidity, with a stable intermediate support structure. The horizontal axial flow pump does not have guide vanes.
4. The forced circulation pump bearing housing is a square long-span heavy-duty structure with good stability, strong load-bearing capacity, reliable operation, and easier installation compared to similar domestic products (the original domestic bearing housing was in a split design). The front and rear ends are equipped with radial short cylindrical bearings and heavy-duty paired bearings. All bearings are of NSK (SKF) or domestic origin.
5. The shaft seal of the forced circulation pump is advanced, utilizing a combination of auxiliary impeller power seal and Bogemann quick-install double-end mechanical seal. It is externally connected to cooling and flushing water, improving the shaft seal working conditions and extending the mechanical seal lifespan. The outer diameter of the shaft sleeve is increased, with thicker wall thickness and less deformation compared to similar domestic products.
Operating Principle of a Forced Circulation Pump
The forced circulation pump transports liquids not by relying on the centrifugal force of the impeller, but by utilizing the thrust from the rotating impeller blades to propel the liquid along the pump shaft. As the pump shaft rotates with the motor, the blades, having a certain helical angle relative to the shaft axis, exert a thrust (or lift) on the liquid, pushing it out and along the discharge pipe. Once the liquid is expelled, a partial vacuum is formed in the original position. Under the force of atmospheric pressure, the external liquid is drawn into the impeller through the inlet pipe. As long as the impeller continues to rotate, the pump can continuously intake and discharge liquids.
