Category Archive: Molten Salts

Advantages and Uses of Molten Salt Heating Systems

Molten salts, also called salt melts, are critical in various industrial heating applications. Nitrate salts are most commonly used in industrial heating applications, but chlorides, bromides, fluorides, and even organic salts are often used for this purpose too. Molten salt process heating systems operate at extremely high temperatures and provide efficient heat transfer and storage. Because of their exceptional thermal properties, molten salt heating systems are used in numerous industries, from power generation to chemical processing.

Keep reading to learn more about the key benefits and applications of molten salt heating systems.

What are the Advantages of Molten Salt Heating Systems?

Molten salt heating systems offer a variety of benefits that make them well-suited for high-temperature industrial applications. Key advantages include:

• Thermal Stability: Molten salts provide excellent thermal stability. They can operate at temperatures higher than 1000 °F, allowing for effective heat transfer in high-temperature processes.
• Efficient Heat Transfer and Storage: Molten salts are highly effective at storing and transferring heat due to their low viscosity and high thermal and electrical conductivity. These salts can store thermal energy for extended periods, making them an excellent choice for processes requiring heat recovery or energy storage.
• Low Vapor Pressure: Molten salts have a low vapor pressure. This reduces the need for heavy piping systems and prevents pressure buildup in heat transfer applications.
• Environmental Friendliness: One of the most beneficial features of molten salts is their environmental friendliness. Molten salts are non-toxic and readily available, similar to commercial fertilizers. Their widespread availability and low environmental impact make them a sustainable option for industrial heating.

Uses of Molten Salt Heating Systems

Due to their numerous benefits, molten salt heating systems are utilized across a wide range of industries, including:

Chemical Recycling

In chemical recycling, molten salts are used for heat transfer in processes like pyrolysis and material recovery applications. For example, molten salts can be used to heat waste tires to break down the rubber and recover valuable materials for other uses.

Steel Processing

The steel industry utilizes molten salt systems for heating and quenching metal. Molten salts facilitate precise temperature control during metal processing, ensuring that steel reaches the optimal temperature for strengthening and shaping.

Thermal Energy Storage in Power Plants

One of the most notable and widespread uses of molten salt heating systems is in solar power generation. Molten salts are utilized to store excess solar energy during the day. This stored energy can then be released to generate steam or electricity on cloudy days or at night. Molten salts have the ability to increase the operational capacity of solar plants from 25% to 70%.

Regeneration Gas Heating

Molten salts are used in regeneration gas heating, particularly for regenerating desiccant and molecular sieve beds. High process temperatures must be adequately managed as natural gas or other fluid streams are fed into molecular sieve beds or desiccant-style drying systems. Once these systems become saturated, molten salt regeneration gas heaters dry the sorbent for the next cycle. Molten salt regeneration gas heaters are also commonly used in air separation applications, where gases like CO2 and water are removed from ambient air.

Contact Sigma Thermal for Molten Salt Heating Systems

Molten salt heating systems benefit various industries, offering efficient heat transfer and thermal storage. These heating systems, from solar power generation to chemical recycling, play a key role in improving energy efficiency and supporting sustainable practices.

At Sigma Thermal, we specialize in designing, engineering, and servicing molten salt heating systems that are tailored to meet your unique needs. Our expert team will learn about your application to ensure your system is optimized for performance and reliability. Contact Sigma Thermal to learn more about our molten salt heating systems or request a quote to get started.

The Advantages of Using Molten Salts for Process Heating

Molten salts, also known as salt melts, comprise a variety of products that are used across many applications. Some applications that rely on molten salts include steel heat treating and annealing, high-temperature process heating, and thermal storage for solar thermal power plants. Depending on the needs of a specific application, different salts are available to use such as chlorides, bromides, fluorides, organic salts, and nitrates. Many applications use a eutectic blend of potassium nitrate and sodium nitrate.While there are several heat transfer fluid options available, molten salts are more ideal for certain applications due to the specific features unique to them.

Why Molten Salts?

There are several advantages of molten salts that make them appealing for use in a wide range of applications. The molten salts that are used most frequently in heat transfer applications are nitrate salts due to their low salt melting point, thermophysical properties, low vapor pressure, high operating temperature, corrosion performance, and low toxicity.

Molten salts help increase the maximum temperature limits in which a liquid heat transfer media can be utilized. Although individual salts are usable in these applications, combining two salts together helps reduce the melting point. The reduced melting point enables lower minimum operating temperatures, which minimizes the risk of freezing. 

For example, the melting point of sodium nitrate is 584 °F or 307 °C, and the melting point of potassium nitrate is 631 °F or 333 °C. Combined, the two salts have a melting point of 431 °F or 222 °C. This melting point significantly expands the salt’s operational flexibility for use in various high-temperature applications.

If an application operates at temperatures exceeding 734 °F or 390 °C and requires a type of liquid heat transfer media, it will need to use a molten salt fluid.

Benefits for Industrial Applications?

A wide range of salt blends can help achieve specific operating temperatures required in certain applications. Compared to hydrocarbon fluids, molten salts experience minimal vapor pressure, regardless of how close operating temperatures are to their limits. As a result, high-pressure equipment and piping are almost entirely unneeded. 

Molten salts are also usable at higher temperatures compared to other fluids such as silicone fluids and synthetic oils. They also have thermal stability and good heat transfer properties. Their high efficiency makes them suitable for use as heat transfer and molten salt energy storage media, as they are eco-friendly and can reduce operating costs. 

Request Your Custom Molten Salt Systems

Depending on your application’s requirements, there are three main types of molten salt heating systems you can use. These include circulated molten salt, salt bath heaters, and direct heating for applications such as metal assembly heat treating. 

At Sigma Thermal, we can provide:

• Circulated molten salt systems that distribute hot liquid salt as a type of heat medium to process heat consumers such as heat exchangers.
• Salt bath heater systems that use natural convection processes and eliminate the need for circulation pumps. This equipment is designed to operate at high temperatures to supply molten salt energy.

Sigma Thermal’s experts design and manufacture a variety of systems that use molten salt energy, including hot salt tanks, circulated molten salt systems, electric heaters, and salt bath heaters. We have the resources and experience needed to design fully automated custom systems. We can help you meet all of your process needs with our innovative solutions.

To learn more about our molten salt systems and get started on a custom solution for your specific application, request a quote today.