Nagle Building Reputation for Molten Salt Pump Expertise

Heavy duty pump design and custom engineering an ideal choice for developing alternative energy technologies

As the world continues to search for viable alternative energy sources, one of the more promising emerging technologies is process heat transfer applications using solar energy to power molten salt loops. A number of high profile universities, governments and commercial entities are currently studying this technology, building out lab-scale test loops and determining how to scale it to production size. Our heavy duty pumps division Nagle Pumps is working with a number of these end users both domestically and abroad via our German division Ruthmann Pumpen.  

The process requires pumps that operate at extremely high temperatures under relatively low flow rates with correspondingly low pressure drops. Pumps rated for 1200° – 2000°F are not conventionally available as stock pumps. With its ability to custom manufacture pumps to exacting end user specifications within tight production timelines, Nagle has made a name for itself as the go-to manufacturer of molten salt pumps.

Primarily, Nagle’s TWO and CWO vertical cantilever pumps have been the design starting point for these highly custom pumps. A huge advantage to the Nagle design is its simplicity. There are no bearings, bushings, packing, seals or rubbing parts below the mounting plate. Less moving parts in contact with the corrosive pumpage limits potential points of failure.

From the standard design, pump materials are upgraded based on the intended temperatures; 316 Stainless Steel is a starting point for the lower end salt temperatures. As salt temperatures increases, Nagle uses higher temperature rated metals in the Inconel and Hastelloy families. All pipe is upgraded from the usual Schedule 40 to Schedule 80.

From there, Nagle works to each individual customer’s specification. A typical modification requested is the addition of spacer pedestals between the mounting plate and bearing pedestal. These spacer pedestals dissipate the heat traveling up the shaft before it enters the bearing pedestal. In these spacer pedestals optional cooling rings, flinger fans, mechanical seals, a labyrinth rotor with packing, or a packed box could also be added. Many of the molten salt pumps also have a non-corrosive insulation box mounted around the shaft just below the mounting plate. Nagle also accommodates the customer’s special requests for additional ports in the mounting plate for monitoring the salt during operation.

Nagle has seen a steady increase in interest in both lab and production scale pumps for molten salt. As they’ve partnered with the leaders in this field, they’ve continued to build on their engineering and manufacturing expertise, preparing them to take on ever more challenging applications.