How to build a molten salt heat exchange system？

1. Design and preliminary preparation

1.1. System design

1.1.1. Determine the type of molten salt (nitrate, chloride, etc.) and the operating temperature range.

1.1.2. Calculate the heat load, flow rate, heat exchange area, and select the appropriate type of heat exchanger (shell and tube/plate).

1.1.3. Design the storage tank capacity, pipeline layout, insulation plan and anti-condensation measures.

1.2. Material and equipment procurement

1.2.1. Molten salt storage tank (high temperature/low temperature tank, usually made of stainless steel or nickel-based alloy).

1.2.2. Heat exchanger (high temperature and corrosion resistance, such as 316L stainless steel or Inconel alloy).

1.2.3. Molten salt pump (high temperature and corrosion resistant centrifugal pump with electric heating function).

1.2.4. Pipes and valves (need to be resistant to high temperatures, usually flanged to avoid welding defects).

1.2.5. Insulation materials (ceramic fiber, rock wool or aerogel insulation).

1.2.6. Electric heating system (to prevent molten salt from solidifying).

1.3. Construction site preparation

1.3.1. Ensure the foundation load-bearing capacity (concrete base is required for large equipment such as storage tanks and heat exchangers).

1.3.2. Reserve safe passages and set up fire prevention and leakage prevention measures.

2. Equipment installation

2.1. Storage tank installation

2.1.1. Low temperature tanks (cold salt tanks) and high temperature tanks (hot salt tanks) are in place and adjusted to the level.

2.1.2. Install monitoring equipment such as liquid level gauges, temperature sensors, and pressure gauges.

2.1.3. Weld or flange the inlet and outlet pipes to ensure tightness.

2.2. Heat exchanger installation

2.2.1. Fixed according to the design position (usually close to the storage tank or steam generator).

2.2.2. Connect the pipelines on the molten salt side and the working fluid side (such as water/steam) to ensure the correct flow direction (countercurrent heat exchange efficiency is higher).

2.2.3. Install a support frame to avoid deformation caused by thermal expansion.

2.3. Molten salt pump installation

2.3.1. Install at the outlet of the storage tank to ensure that there is enough net positive suction head (NPSH) at the suction end.

2.3.2. The pump body and the motor are connected with a high-temperature coupling, and a shock-absorbing base is installed.

2.3.3. Matching electric heating cable to prevent molten salt from solidifying during shutdown.

2.4. Pipeline system installation

2.4.1. Use flange connection (for easy maintenance) to avoid stress cracking caused by welding.

2.4.2. The pipeline layout needs to have a slope (inclined to the storage tank or discharge port) to facilitate the emptying of molten salt.

2.4.3. Install expansion joints at key locations to compensate for thermal expansion and contraction.

3. Insulation and electric heating construction

3.1. Insulation layer construction

3.1.1. Wrap the storage tank, heat exchanger and pipeline with ceramic fiber blanket or multi-layer composite insulation material.

3.1.2. Add aluminum or stainless steel sheath on the outer layer to prevent mechanical damage and rain erosion.

3.2. Installation of electric heating system

3.2.1. Wrap the self-controlled temperature heating tape around the molten salt pump, valve and easy-to-solidify pipe section.

3.2.2. The temperature sensor is linked to control to maintain the pipeline temperature higher than the solidification point of the molten salt (such as solar salt requires >220°C).

4. System testing and debugging

4.1. Pressure test

4.1.1. Use inert gas (such as nitrogen) or water to test the pipeline pressure and check the leak point (molten salt system usually requires 1.5 times the working pressure test).

4.2. Molten salt filling

4.2.1. Preheat the system to above 150°C (to prevent the molten salt from solidifying).

4.2.2. Heat the solid salt and melt it, then pump it into the cold salt tank and circulate it to the entire system.

4.3. Hot commissioning

4.3.1. Gradually heat up to the operating temperature (such as 290°C–565°C) and monitor the thermal expansion of each component.

4.3.2. Test heat exchange efficiency, pump flow, and control system response (such as PID adjustment).

4.4. Safety interlock test

4.4.1. Simulate faults (such as power failure, overtemperature) and verify safety measures such as emergency discharge valves and backup power supplies.

5. Operation and maintenance

5.1. Daily inspection: monitor the molten salt level, temperature, and pump vibration.

5.2. Anti-corrosion management: regularly sample and analyze the molten salt composition (to prevent impurities from accelerating corrosion).

5.3. Shutdown maintenance: After draining the molten salt, purge the pipeline with dry nitrogen to prevent moisture absorption and corrosion.

 

6. Key points

6.1. Anti-solidification: Keep the electric heating running or drain the molten salt completely during shutdown.

6.2. Anti-leakage: Leakage of high-temperature molten salt may cause fire, and an emergency discharge system is required.

6.3. Material compatibility: Avoid contact between non-corrosive materials such as carbon steel and molten salt.

7. Typical application case assembly example (solar thermal power station)

1. Tank in place → 2. Install heat exchanger and steam generator → 3. Lay molten salt pipeline → 4. Add insulation and electric heating → 5. Pressure test and molten salt filling → 6. System joint commissioning and grid connection

 

By strictly following the assembly process, the molten salt heat exchange system can be ensured to operate stably for a long time, which is suitable for high-temperature scenarios such as solar thermal power generation and industrial waste heat utilization.

 

Related links:

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