【2026 Transmission Equipment】Excessive pressure fluctuations at the outlet of the reciprocating pump
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The outlet pressure of the reciprocating pump fluctuates excessively (±0.5 MPa); how can it be stabilized? The pressure fluctuations in reciprocating pumps are essentially the result of the \"positive displacement delivery characteristics\" combined with \"changes in system resistance\", and adjustments to these two factors yield immediate effects. 1. Install a buffer: A bladder-type buffer (with a capacity 3–5 times that of a single cylinder’s displacement of the pump) should be installed in the outlet pipeline near the pump body to absorb pressure fluctuations; after its installation, the pressure variations were reduced from ±0.6 MPa to ±0.1 MPa ； 2. Optimize pipeline design: reduce the number of elbows in the outlet pipelines (≤3), increase the pipe diameter (keep the flow velocity between 1.5–2.0 m/s), and minimize fluctuations in pipeline resistance ； When transporting viscous media (viscosity > 500 cP), heat tracing is required to prevent fluctuations in resistance caused by changes in viscosity.
Below: Centrifugal pump vs. axial flow pump, for reference. Centrifugal pump: Uses centrifugal force to \"fling\" water out. Axial flow pump: Works like a propeller, \"pushing\" water forward. One relies on flinging, the other on pushing; their principles are completely different, and their application areas vary greatly as well.
I. Axial flow pump: The “propeller” in pipelines, moving in a straight line. Axial flow pumps belong to the category of vane pumps, and their main characteristic is that the liquid flows in the direction of the pump shaft, without any turning or change in direction.
1. Working principle: The impeller of an axial flow pump is similar to a marine propeller, with blades shaped like wings. During rotation, the blades generate lift and thrust on the liquid, directly \"pushing\" the fluid forward in an axial direction. No radial ejection, no 90° turns, a straight path the entire way.
2. Core structure: Rotor: The key component that performs work, featuring propeller-style blades that generate axial thrust. Guide vane: Installed behind the impeller, it straightens the rotating water flow, eliminates vortices, and converts kinetic energy into pressure energy. Straight-through flow channel: The inlet and outlet are on a straight line, with the fluid undergoing almost no turning.
3. Features: High flow rate, low head; small footprint, high efficiency. Widely used in circulating water systems, drainage, and high-flow transportation
II. Centrifugal pumps: The most common type of \"water-dispelling pump\". Over 90% of the pumps used in chemical plants are centrifugal pumps. Their working principle is well-known: water is drawn in axially and discharged radially, first being accelerated and then pressurized.
1. Working principle: Suction: Liquid is drawn in from the center of the impeller, creating a low pressure at the center. Acceleration: The high-speed rotating impeller uses centrifugal force to throw the liquid toward the edges, achieving maximum velocity. Pressure conversion: High-speed liquid enters a volute shaped like a snail shell; as the flow channel widens gradually, the flow velocity decreases, and kinetic energy is converted into pressure energy, which is used to push the water out. Simply put: the impeller is responsible for acceleration, while the volute is responsible for pressurization.
2. Features: Low to medium flow rate, high head pressure; capable of generating high pressure and delivering fluid to high locations (distillation towers, reactors, surge tanks). It has the widest range of applications and can be used with various types of fluids
The most vivid analogy: Centrifugal pump: like a spin dryer that flings water out; Axial flow pump: like an electric fan that pushes air (water) straight forward