Pumps for discerning membran filter systems

Three centrifugal pumps from DICKOW Pumpen are installed in this membrane filter system: a circulation pump, a high pressure pump and a wash and feed pump.

Effectively cleaning of waste water and recovering of reusable materials

A Norwegian Company is building membran filter systems for operators in the pharmaceutical, biotechnological and chemical industries, to make contaminated water recyclable and return filtered solids to the raw material cycle. The technology is promising for the future, but also cost-intensive and requires the use of reliable and high-quality components. The heart of the system is made up by centrifugal pumps from DICKOW.

Membrane technology can be used to make raw water with a wide variety of contamination in variable concentration, for example concentrated brine, and also to remove microorganisms and viruses. The production of pharmaceuticals and vaccines is therefore a scope of application of the membrane filter system from the nordic manufacturer.

Operating mode of the system

In the membrane filter system, a membrane made of porous material is installed, which filters the contaminations and particles from the liquid. The size of the pores can be varied depending on the application and requirement. The heart of the system is formed by the pumps, which supply the medium through the system at different pressures. In addition, the requirements for the pumps used in the membrane plants are very different. For example, a operator concentrates salty contrast media, washing out the salts. The pumps in this system must provide a high flow rate and pressure. In addition, they must be made of corrosion-resistant materials that are resistant to saline liquids and other aggressive media, since saline contrast media have the property of corroding and damaging metal parts. For this installation Dickow designed and supplied three different centrifugal pumps, the circulation pump, the high pressure pump as well as the wash and feed pump.

Heavy duty circulation pump

The NCL single-flow volute casing pump was selected as the circulation pump. It is designed to move large volumes of media through the filtration system at low pressure to ensure that it is distributed evenly across the membrane. Continuous circulation of the fluid ensures that the membranes are used evenly and avoids areas that can become clogged due to stagnant fluid. The pump has a heavy-duty construction designed for continuous use. It consists of a casing with an inlet and an outlet and an impeller. When the volute casing pump is in operation, the impeller rotates inside the casing, creating a centrifugal force that moves the fluid from the center of the casing to the edges.

The fluid is drawn into the pump through the inlet and forced outward by the rotation of the impeller, assisting the natural flow of the fluid through the shape of the volute casing and converting the flow velocity into pressure energy. Fluid is discharged into the system through the pump outlet.

An NCL was selected for the contrast media desalination system, which delivers 140 m³/h with a pressure of 16 bar. At this point, a low-pressure pump is actually sufficient.

The NCL volute casing pump, also a chemical standard pump, designed for difficult media and high pressure.
Cross-section of the NCL volute casing pump: the accurate design of all components results in maximum efficiency and long service life.

Powerful high pressure pump

The DICKOW high-pressure pump is one of the most important components of the membrane filter system. It generates the necessary pressure to force the medium through the membranes. The requirement is high performance and efficiency to ensure that the salty contrast medium is thoroughly purified. The higher the pressure, the more effective the filtration. For this purpose, the HZAR multistage centrifugal pump was selected, whose pump housing consists of several elements. The elements are individual stage casings, which are connected to each other in tandem and each supply energy to the rotating shaft of the medium by means of an impeller in a liquid-tight and pressure-resistant pump interior. The individual stage casings are interconnected to form a continuous chamber. In this way, the pressure on the medium is increased in proportion to the number of elements and the medium can be handled at high pressure. The HZAR that was selected for this plant has seven stages and can generate a pressure of 36 bar with it. With a flow rate of 70 m³/h, a continuous stream within the mechanism is achieved.

The HZAR a multistage chemical standard pump for high pressure

Effective filter cleaning

The wash and feed pump is installed in the system for cleaning the filter system. They remove contaminations and deposits from the membranes, which are deposited during the filtration process. To clean the filter system quickly and effectively, a high flow rate is required. For this application the NCB volute casing pump is recommended. It is particularly suitable for washing membranes in a membrane filter system, as it is suitable for delivering a high flow rate of 80 m³/h at a relatively low pressure of 16 bar. This effectively and thoroughly cleans the membrane, resulting in a longer service life and higher performance of the membrane filter system.

Reliable and low maintenance

All DICKOW pumps used in the membrane filter system are made of high-quality materials and are designed for durability and reliability. A further benefit of the centrifugal pumps is their simple design with a relative small number of moveable parts. For example, only one maintenance of the bearings and the mechanical seal is required at regular intervals. If maintenance should be almost eliminated, the use of magnetic pumps is recommended. This would also avoid the replacement of the mechanical seals.

Source & Pictures: DICKOW Pumpen

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