Industrial heat-transfer salts · Blended to order
Industrial salt blends and technical support for high-temperature processes. Find the right blend for your application and connect directly with our team.
Or reach us directly: 281-954-1567 · will.bridges@moltensaltsupply.com
1 / 7 The loop
A pump circulates molten salt around the reactor, through an external heat exchanger, and back again. The salt is the heat-transfer medium: it carries heat; it doesn’t make it.
This is one illustrative arrangement. Real systems vary, and ancillary equipment is left out for clarity.
2 / 7 Inside the reactor
A shell-and-tube reactor holds a large bundle of metal tubes. Process material reacts inside the tubes; the salt circulates through the shell outside them, guided by baffles.
The two never mix. Heat crosses the tube walls.
3 / 7 Into the melt
Above its melting range, a nitrate/nitrite blend is a free-flowing liquid. Original Blend’s nominal fresh-blend melting point is about 288°F (142°C).
Its vapor pressure stays low at operating temperature, so the salt side doesn’t need to be pressurized to stay liquid. The pump still develops pressure, and the process side has its own.
4 / 7 What it’s made of
Molten salt isn’t made of molecules of “salt.” It’s a liquid of positive sodium and potassium ions and negative nitrite and nitrate ions, all moving past one another.
Original Blend is 40% sodium nitrite, 7% sodium nitrate, and 53% potassium nitrate by mass, which works out to roughly 49 : 7 : 44 by count of formula units.
In service, some nitrite oxidizes to nitrate and carbonate can build up, shifting the melting point. Sample analysis tracks exactly that.
Nitrite (NO₂⁻) is one nitrogen with two oxygens, bent. Nitrate (NO₃⁻) is one nitrogen with three, flat.
5 / 7 Heat crosses the wall
In cooling duty, the reaction inside the tube is hotter than the salt outside. Heat moves by convection to the tube wall, by conduction through the metal, and by convection into the salt.
The particles stay on their own side. Only energy crosses. The amber rings are an overlay showing heat direction, not a color the salt turns.
6 / 7 Carried away
The salt leaves the shell somewhat warmer and flows out through the hot line. It doesn’t boil or change phase; it simply carries the heat it picked up.
The rate is roughly Q̇ ≈ ṁ × cₚ × ΔT: mass flow, times specific heat, times temperature rise. More flow means a smaller rise for the same heat load.
7 / 7 Released, then returned
In the external exchanger, the salt passes heat through more tube walls to a separate utility stream, for heat recovery or utility cooling. Then it returns cooler to the pump and starts again.
Want to talk through your system? We supply the salt and the technical support to keep it in spec.
Heat-transfer salts blended to order, so they don't sit in a warehouse picking up moisture. Every quote starts with what your system needs.
For initial fills and replacement fills in nitrate/nitrite heat-transfer salt systems.
| Component | Share |
|---|---|
| NaNO2Sodium nitrite | 40% |
| NaNO3Sodium nitrate | 7% |
| KNO3Potassium nitrate | 53% |
Nominal fresh-blend melting point about 288°F / 142°C.
For systems whose salt chemistry has drifted, or that need a composition other than the Original Blend.
In service, some nitrite can oxidize to nitrate, which raises the melting point. A butting salt blend can move the inventory back toward its target composition. We work from your analysis and review the options with you; we don't prescribe a blend without it.
For concentrating solar power (CSP) plants, as both thermal energy storage (TES) and heat-transfer fluid. We offer a Binary Solar Salt Blend and a Solar XL Blend.
Sodium nitrate (NaNO3) and potassium nitrate (KNO3)
Compared with traditional molten salt (KNO3–NaNO2–NaNO3) in solar applications, it offers improved thermal performance through higher energy density, so a smaller quantity stores the same amount of heat. It also has a lower melting point, higher thermal stability, and a wider operating window.
Sodium nitrate (NaNO3), potassium nitrate (KNO3), and calcium nitrate (Ca(NO3)2)
Compared with traditional molten salt in solar applications, it has a lower melting point, higher thermal stability, a wider operating window, and cost efficiency compared with other blends. Its higher energy density also improves thermal performance, so a smaller quantity stores the same amount of heat.
2,000 lb super sacks, or 50 lb bags on pallets.
Certificate of Analysis available with every order. Request product documentation.
The same loop as a labeled diagram you control. Switch between removing and supplying process heat, step through the stages, or open the tube-wall close-up. The salt is the heat-transfer medium. It carries heat; it doesn't make it.
Cooling duty: the reaction releases heat and the salt carries it away.
For a single-phase salt stream, the rate of heat transfer is Q̇ ≈ ṁ × cp × ΔT: how much salt flows each second (kg/s), times how much energy each kilogram takes to warm by one degree (kJ/kg·K), times how much its temperature changes (K). The result is power, in kW.
Energy stored or released by a quantity of salt is E ≈ m × cp × ΔT, in kJ or MJ. Power is a rate; energy is an amount. 3,600 kJ = 1 kWh.
Illustrative temperatures—not operating recommendations.
Salt enters the reactor shell at 330°C and leaves at 350°C (ΔT = 20 K). With an assumed cp of 1.5 kJ/kg·K and 10 kg/s of flow, Q̇ ≈ 10 × 1.5 × 20 = 300 kW. The external exchanger returns the salt to 330°C. At the same heat load, doubling the flow to 20 kg/s halves the temperature rise to about 10 K.
Cooling 20,000 kg of salt by 20 K releases E ≈ 20,000 × 1.5 × 20 = 600,000 kJ, about 167 kWh.
Assumes constant cp and negligible heat losses. Real properties vary with blend composition and temperature, so use data for your specific salt.
Colors in the drawing show relative temperature only; they aren't what molten salt looks like. These salts are industrial chemicals that need proper handling. See the SDS and technical resources.
These processes run reactions that only behave within a narrow temperature window. Salt circulating around the reactor tubes takes heat away when the reaction releases it, or supplies heat when the reaction needs it, so the process stays where it should.
Each plant's operating conditions are its own. Tell us about yours and we'll discuss the right salt for it.
Salt chemistry changes in service. Nitrite oxidizes, carbonate builds up, and the melting point moves. An analysis shows where your inventory stands, and our written evaluation explains what the results mean for your system and your blend needs.
We'll confirm sample details when we follow up. Results inform a conversation; they don't guarantee a specific correction.
Standard analysis
Additional tests are available. Ask us for the current list.
Updated technical documents with plain explanations, including composition diagrams and carbonate solubility curves, plus help comparing blend options for your system.
Some spent salt can go to other industries that use similar salts instead of disposal. Whether yours qualifies depends on testing, for example for hexavalent chromium and excess carbonate.
In two-tank thermal storage, hot and cooler liquid salt sit in separate insulated tanks. Moving salt between them stores heat and releases it when it's needed, the approach used in concentrating solar power.
This is a separate storage configuration that uses an application-appropriate blend, such as a solar salt. It isn't part of the reactor loop above, and Original Blend limits don't carry over to it.
Charge. Cooler liquid salt is pumped through a heat source and into the hot tank. The hot tank fills as the cooler tank empties.
Above its melting range, a suitable salt blend is a pumpable liquid with useful heat capacity and density and low vapor pressure, which makes it practical at high temperatures. Per kilogram it holds less heat than water; its advantage is staying liquid, at low pressure, where water would need a high-pressure system.
External sources for general principles. They are not affiliated with Molten Salt Supply and are not product specifications.
Molten Salt Supply, LLC supplies industrial heat-transfer salts and the technical support to keep them working. Our technical expert brings 25 years of experience with molten salt systems: chemistry, analysis, supply, and consultation.
We blend to order in ribbon blenders on load cells, so the composition you receive is the composition you ordered, and the salt doesn't wait in a hot warehouse absorbing humidity and bricking up. The Original Blend follows the nitrite/nitrate composition that industry has studied and used for decades.
Talk to us directly: 281-954-1567 or will.bridges@moltensaltsupply.com.
A few details are enough to start. You don't need to know the chemistry. We review each request and follow up with you directly.
