Molten Salt Storage in Coal Power Units: Changyuan Power Jingzhou’s Heating and Peak Shaving Project
As global power systems continue to adopt higher levels of renewable energy, traditional coal-fired power units face new challenges: how to provide flexible, rapid response to load fluctuations while maintaining heating supply reliability and reducing emissions. One of the most promising solutions today is the integration of molten salt energy storage into coal power plants—an innovation already being implemented in China’s leading demonstration project: the Changyuan Power Jingzhou Heating and Peak Shaving Project.
This article provides a clear, practical explanation of how molten salt storage works in coal units, why it is becoming a preferred technical route for flexibility retrofits, and how high-temperature molten salt pumps—such as those supplied by SDP Pump—play a critical role in system stability, thermal cycling, and safety.
1. Background: Why Coal Units Need Flexibility Transformation
With increasing penetration of wind and solar power, grid operators require dispatchable power sources that can quickly ramp up and down. Traditional coal-fired units were originally designed for baseload operation, not for highly flexible cycling.
Key challenges include:
- Slow response to peak–valley load changes
- Thermal stress on boilers during frequent ramping
- Significant fuel consumption during low-load operation
- Difficulty meeting both electricity supply and centralized heating needs
- Higher emissions under part-load conditions
To solve these issues, advanced coal plants are being upgraded with molten salt thermal storage, effectively turning the units into hybrid thermal–energy-storage systems with improved ramping capability and stable heating output.
2. How Molten Salt Storage Works in Coal Power Units
Molten salt—typically a sodium–potassium nitrate mixture—is an ideal high-temperature heat transfer and storage medium due to its:
- High thermal stability (operating 290–565°C)
- High specific heat capacity
- Non-flammability and low cost
- Long service life
Basic Working Principle
- Heat Charging
- When the coal boiler operates at higher load or during low electricity prices, surplus heat is transferred to a molten salt tank via a high-temperature heat exchanger.
- Molten salt absorbs the heat and stores it as thermal energy.
- Heat Discharging
- During peak electricity demand or when heating supply is required without increasing boiler load, the system extracts heat from the molten salt tank.
- The stored energy supports steam generation, district heating, or other peak-shaving needs.
Benefits
- Enables fast and predictable peak shaving
- Reduces boiler thermal stress
- Ensures stable heating capacity even at low load
- Improves plant efficiency and reduces fuel consumption
- Enhances overall grid flexibility
This hybrid approach transforms a conventional coal plant into a flexible, low-carbon and high-efficiency energy hub.
3. About the Changyuan Power Jingzhou Molten Salt Project
The Changyuan Power Jingzhou Company’s heating and peak-shaving retrofit is one of China’s benchmark molten salt–based coal unit upgrades. It introduces a high-temperature molten salt storage system capable of absorbing and releasing heat during peak and off-peak cycles.
Key highlights include:
- Molten salt system integrated into a coal-fired heating unit
- Significant improvement in flexibility, supporting rapid load swing
- High operational reliability for long-term district heating supply
- Reduction of boiler cycling and emissions
- Better alignment with China’s dual-carbon goals (carbon peak & neutrality)
This project demonstrates the feasibility of large-scale molten salt integration in coal units and offers a replicable model for other regions.
4. Why Molten Salt Pumps Are the Core of the System
The heart of every molten salt storage system is its molten salt pump—responsible for circulating the 300–600°C molten medium across heat exchangers, tanks, and process loops.
Because molten salt solidifies below ~240°C, pumps must withstand:
- Extreme temperatures
- Thermal shock from cycling
- Corrosion resistance
- Long continuous operation
Key Pump Requirements
- High-grade alloy materials (e.g., Cr–Ni, superalloys)
- Special lubrication design for high temperature
- Extended shaft and insulation structure
- Sealless or advanced sealing options
- Robust bearings with thermal protection
SDP Pump provides high-temperature molten salt pumps engineered for CSP, energy storage, electric boilers, and coal-unit retrofits. Their pumps are designed to deliver stable circulation of molten nitrate salts under high load and long-duration operation, ensuring safety and reliability throughout charging and discharging cycles.
5. How Molten Salt Storage Enhances Heating and Peak Shaving
For cogeneration plants like Jingzhou’s, molten salt systems offer several real operational advantages:
✔ Stable Heating Output
Even when the coal boiler is operating at minimum technical load, molten salt storage can release heat to support district heating networks—avoiding thermal fluctuation for end users.
✔ Peak Shaving Without Increasing Boiler Load
When electricity demand spikes, stored heat supports additional steam generation without needing rapid combustion increases—protecting the boiler.
✔ Higher System Efficiency
Heat recovered and stored during low-load periods is not wasted, improving energy utilization and reducing fuel demand.
✔ Reduced Emissions
By preventing unnecessary low-load operation and reducing cycling, emissions of SO₂, NOx, and CO₂ are significantly lowered.
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