The pumped liquid in a pipeline centrifugal pump is usually heated by the heat exchanger

Pumps in pipeline transportation systems generate sound waves that propagate as guided pressure transients in the transported fluid. Using data-driven techniques, these signals can be used for automated remote monitoring of the pump integrity without any prior supervisory information.

Suction pipe diameters should be larger than the discharge flange size to reduce friction losses and decrease energy cost. Larger pipes also prevent air entrainment, which can cause loss of performance, noise and vibration.

Pressure

A centrifugal pump uses an engine or motor to rotate an impeller attached with vanes that are forced against the casing. This creates pressure inside the casing and forces water toward the periphery of the pump’s delivery pipe. This pressure is then released through the discharge valve.

Centrifugal pumps are built of a variety of materials, each designed for specific applications and operating conditions. For example, cast iron provides high tensile strength and abrasion resistance correlated to a high-pressure rating, while stainless steel is resistant to corrosion. The type of material a pump is made from affects its price, performance, durability and maintenance costs.

To reduce pressure pulsation, it’s best to use suction pipework that is one or two sizes larger than the pump inlet flange. Larger diameter piping means less friction losses and reduced energy costs. It’s also advisable to use an eccentric reducer orientated to eliminate the possibility of air pockets in the suction pipe. This helps to keep the pipe velocity below 2 m/s which reduces turbulence and lowers vibration levels.

Temperature

The pumped liquid in a pipeline centrifugal pump is usually heated by the heat exchanger. As the temperature rises, so too does the internal pressure and the horsepower required to achieve a given flow and head. This is because the lower density of hot water requires less energy to push a given volume of liquid.

The higher temperature also reduces the film thickness between the mechanical seal faces, leading to increased friction and decreased lubrication. In addition, the lower viscosity of the fluid makes it harder for the pumped fluid to fill the space between the non-contacting rotors in the pumping chamber.

In order to mitigate this issue, a minimum flow bushing can be added to the bottom of the pump’s seal chamber. This separates the cooler water in the seal chamber from the hotter water in the pump casing and reduces backflow from the seal chamber. This is especially important in high-pressure, high-temperature applications.

Flow

The flow of a pipeline pump is measured in units of volumetric flow rate per hour. Generally, the higher the flow, the more energy is required to operate the pump. However, a variable speed drive is used to achieve the same fluid flow with significantly less power (brake horsepower).

The liquid enters the pump casing and is forced outwards at high velocity creating pressure which is the head. The liquid passes through a diffuser which is shaped with continuously increasing area. This reduces the velocity and increases the pressure again.

A typical performance curve shows a series of flow versus head curves. The points where the two curves intersect represent a maximum capacity for the pump.

Noise

Pumps are a large component of oil pipelines. Their noise is a major source of nuisance. This can be reduced by using noise-absorbing materials and by locating the pumps away from busy roads or residential areas.

Moreover, pipeline pumps can be augmented with positive displacement (PD) pumps as a means of reducing energy costs and operational issues associated with the pumping of viscous oil. PD pumps move constant volumes of fluid with each operating cycle, which helps maintain steady flow and pressure.

The main component of a centrifugal pump is the impeller, which has an arrangement of backward-curved vanes. An electric motor drives the impeller, which imparts velocity to liquid. The suction and discharge nozzles are provided to allow the liquid to enter and exit the pump. Pump bearings support all loads imposed on the pump and keep shaft deflection within acceptable limits. The drive seals prevent leakage and wear. The air gap between the pump chamber and the motor eliminates heat transfer, which reduces friction loss, pulsation, and noise.