Critical valves – Best practices for CSP & MSR – Molten salts applications

industrial valves for molten salts Guichon

” The beginning is behind us but the best is yet to come.”

Since the 70’s, several types of molten salts have been used in various industrial applications. The general chemical industries already have a good experience with them and developed interesting technical solutions to face with the technical constraints on production units. Sodium, Potassium, Lithium production plants are some of these.

Nowadays, the power industry takes the advantages of these molten salts in substitution of conventional transfer fluid (heated oils, steam). That is the case on a Concentrating Solar Plant (CSP):

The main goal: Heating the molten salts with the sun power and store them during the day. They will be re-used during the night and provide heat to the steam generator in order to generate electric power all night long.

molten salts scheme guichon valves solutions molten salts scheme guichon valves solutions

The latest commercial units have been tested and results are exciting! One of the conclusion is that the global profitability of a CSP is depending on valves reliability: Design Improvement is worth-it!

Install the right valve technology: It is not that easy!

Some nuclear activities started to go forward with molten salts as well. But whatever is the application, the fundamental process technical challenges regarding the valve are the following:

  • Molten salts lines are working at High Temperature (more than 600°C/1115°F).
  • Corrosive fluids (depends about the type of salts: Chloride, fluoride, sodium nitrate NaNO3, potassium nitrate KNO3…etc.)
  • High flow velocity
  • High reliability & long-life / No down-time required
  • Perfect tightness (inline and process/atmosphere)

Several custom-made solutions are able to fit the process requirements coming from the main EPC contractors and licensors sepcifications (EDF, ENGIE, ACWA, INNOGY, JGC, SENER, ABENER, ABENGOA…)

Backed with more than 40 years of experience in molten salt applications, Guichon Valves designed several tailored valve solutions:

“Golden Rules – Good practices to keep in mind regarding valve selection”

For each molten salt environments, it is advised to select your valves according to the following points:

  1. Always use a welded or forged valve body. A usual and classic cast design is not appropriate (carbon ratio is too high and impurities could be a big issue…).
  2. Use stainless steel to manufacture the valve body and trim (depends about the fluid type and concentration).
  3. Use alloys lining on critical surfaces in order to optimized the chemical resistance.
  4. Never use ball valve (they are just not appropriate. The leakage class is too important for molten salt applications). Prefer gate, slide, globe or piston valves (butterfly valves could also be a cheaper alternative).
  5. If the salts stay liquid (hot valve), it is better to use a bellow-seal valve.
  6. If the salts become solid (cold valve), the classic stem design without bellow is acceptable.
  7. Do all the valve calculations (thermal, mechanical, actuator sizing…etc.) in order to avoid any sticking of the valve or salts solidification.
  8. And more…(o’rings shapes and materials : graphite, nickel, nimonic, dead zones, cleaning nozzles, jacket and heat tracing…etc.)

Please ask for more information.

Know more about our valves for molten salts

Written by Rudy Repellin