5 industrial sump pumps

Magnetic Drive Chemical Pumps in Flow Battery Applications

How Do Flow Batteries Work?

In a flow battery, negative and positive liquid electrolytes are pumped from large storage tanks through separate loops to porous electrodes separated by a membrane. During discharge, electrons freed by reactions on one side travel to the other side along an external circuit, powering devices on the grid. During charging, the opposite set of flows and reactions occurs as the battery stores power.

The power (MW) of a flow battery system is determined by the surface area of the ion-selective membrane, and the capacity (MWh) of the system is determined by the volume of the liquid electrolyte storage tanks. The length of operation can be increased by simply adding additional electrolyte storage capacity.

What Type of Electrolytes Are Used?

Different flow battery manufacturers use different types of electrolytes. Zinc bromide was the original material, which has since been replaced by other materials, including hydrogen bromide/diatomic bromine, vanadium-based, iron/salt/water-based and others.

How Are Electrolytes Moved Through Flow Batteries?

Magnetic drive centrifugal chemical pumps are used to move the electrolytes in the systems. Centrifugal pumps use rotational energy supplied by an impeller to move safely and efficiently at a wide range of flows. From applications less than 1 gallon per minute (gpm) (≈ 3.8 liters per minute [lpm]) to greater than 1,400 gpm (≈ 318 meters cubed per hour [m3/hr]), there is a size to fit any flow battery design.

Magnetic drives can eliminate the need for the mechanical seal found in other types of centrifugal chemical pumps. Mechanical seals typically contain metal, which can allow external components to potentially become electrified. In a magnetic drive centrifugal pump, there is no direct connection between the impeller and the motor shaft. Magnets are mounted on the motor shaft to transfer the motor power through a solid nonconductive barrier to other magnets inside the pump. These magnets rotate the impeller to move the fluid, preventing any electrification of external components.

The centrifugal design produces the smooth, pulseless electrolyte flow required for flow batteries to operate properly.

Mechanically sealed chemical pumps require routine seal replacement or repair that can make them costly to operate. Fortunately, magnetic drive centrifugal chemical pumps have low maintenance requirements. This low maintenance not only reduces the long-term cost of ownership but also decreases downtime, which is critical in flow battery applications.

Other benefits of magnetic drive centrifugal chemical pumps include:

Corrosion resistance: Magnetic drive centrifugal chemical pumps are manufactured using corrosion-resistant materials. This construction allows them to withstand the harshest chemicals and conditions inside and out. Environments that would quickly break down other pumps are not an issue for their corrosion-resistant design. Some flow batteries use electrolytes that are corrosive.

Electrically insulated construction: Magnetic drive centrifugal chemical pumps have nonconductive material options like glass-filled polypropylene and unfilled ethylene tetrafluoroethylene (ETFE). These nonconductive materials prevent any electrical flow from the charged electrolytes to the exterior of the pump. The ability to have this option is a critically important safety feature for flow battery applications.

Magnetic drive chemical pumps are a solid choice for flow batteries and have had a proven track record in flow battery applications for more than 25 years. The durable design will allow for continuous, long-lasting performance in flow battery applications, helping users meet the increasing number of regulatory demands to eliminate fossil fuels.