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Hydraulic Pumping Applications in the Chemical Industry

The chemical industry employs both centrifugal and positive displacement pumps to satisfy the needs of a broad range of pumping applications. The selection of the type of pump, however, is based on several factors, such as the type of material being pumped, the environment and the flow/pressure requirements of the application.

Centrifugal pumps are applied to increase pressure and the flow rate of a fluid in a piping system. These pumps apply a centrifugal force to fluids via a rotating impeller that accelerates the flow rate of the fluid from the suction side to the discharge side of the pump. On the other hand, positive displacement pumps are used to establish fluid flow by capturing a fixed volume of fluid in the pump’s cavity and hydraulically forcing it out to the discharge section of the pump. Since the same flow is produced at a given speed or discharge pressure, positive displacement pumps are defined as constant flow devices.

Centrifugal Pump Applications

Centrifugal pumps are broadly used in the chemical industry for transferring raw fluids, sludge, slurries, and finished chemical & petrochemical products. They are well suited for moderate to high flow applications with a low-pressure head. They are simple machines with low maintenance requirements. They operate with uniform flow and are easily adapted to electric motor or turbine drives. The types of centrifugal pumps used in the chemical industry include: radial flow, axial flow, mixed flow, sand pumps, submersible slurry, shear, charging, among others.

The use of centrifugal pumps in a multiphase configuration is common to oil drilling applications because of their simplified field installations, cost reduction potential and greater productivity. Multiphase pumping will typically connect smaller pumps in series to transfer raw fluid flow from oil wells to processing plants located down stream. They can be installed onshore or offshore and are designed to function in variable processing situations.

Positive Displacement Pump Applications

Positive displacement or reciprocating pumps are regularly used in the chemical and petrochemical industries for pumping chemicals, fuel oil, sea water, paints, corrosive fluids, waste, crude oil, sand, hydraulic oil, resin, reagents, acids, sludge, biodiesel, emulsions, condensates, petroloeum spirit, diesel fuel oil, dyes, among others. They are predominantly applied in low flow and high-pressure head applications.

The types of centrifugal pumps used in the chemical industry include: vane, piston, diaphragm, progressive cavity, rotary gear, peristaltic, multi-screw, helical rotor, reactor circulating, and others. Helical rotor pumps are useful for submersible and waste applications, while helical gear pumps are used for pumping thick fluids. Vane pumps are typically applied in high-pressure applications. Reactor circulating pumps are used in batch operations where viscosity changes over the course of the process. Circulating pumps can contain heat exchangers to transfer energy produced during the chemical reaction.

Positive displacement pumps have the added advantage of being able to pump fluids containing large amounts of gas, which is not possible with centrifugal pumps because doing so would create a gas or vapor binding condition, which prevents the impellor from sustaining the flow. This feature of positive displacement pumps is especially useful in the petroleum industry because pre-refined oil is typically a mixture of oil, gas, sand and water. Using positive displacement pumps, this raw mixture can be pumped to a processing facility via a single pipeline where it can then be separated into its component parts.