The reliability of a boiler control system is critically important, especially during unexpected situations such as power failures or network disruptions. Many users are concerned about whether their control systems can maintain boiler safety in such events. A high-quality boiler control system should be designed with robust fault tolerance and backup strategies to ensure that essential safety interlocks and protective operations continue to function even under extreme conditions. Henan Rentai Electric Equipment Co., Ltd. places high importance on safety redundancy in its control system design. Through a multi-layered hardware and software approach, the company ensures that its control systems maintain fundamental safety functions even in cases of power outages or network failures.
Impact and Protection Measures for Sudden Power Failures
A sudden power outage is a serious industrial risk. If power supply to an operating boiler is interrupted, key components such as forced draft fans, induced draft fans, and feedwater pumps will stop working, and control instruments will lose power. However, the boiler still contains a significant amount of fuel and residual heat, which can lead to dangerous situations:
If the burner flame is extinguished but the fuel valve remains open, there is a risk of fuel leakage and explosion.
If the circulation pump stops, it could cause the boiler to overheat or generate excess steam pressure.
For solid fuel boilers, a stopped fan can cause the furnace temperature to rise rapidly, potentially leading to combustion chamber explosions or overheating damage.
To mitigate these risks, the control system must immediately execute key safety actions during a power failure:
Shut off fuel supply
Activate emergency pressure relief or cooling measures
Store critical operational data
Ensure a safe system restart after power restoration
Henan Rentai’s control systems incorporate the following safety measures to handle power failures:
1. Fail-Safe Design
The fuel shut-off valves and ignition valves used in Rentai’s control systems adopt a normally closed or power-off closure design.
When the power supply is lost, these valves automatically close due to spring force, physically cutting off fuel flow.
For instance, the main gas valve on a gas-fired boiler is configured to close upon power loss, ensuring that no gas enters the furnace.
This intrinsic safety design aligns with international safety standards.
For example, U.S. Coast Guard Regulation 46 CFR mandates that if power is lost, all fuel valves must close automatically within 4 seconds.
Henan Rentai strictly follows these safety standards to ensure that boilers enter a "safe shutdown" state during power outages.
2. UPS Backup Power
To maintain critical control functions during power outages, Henan Rentai can equip its control systems with an Uninterruptible Power Supply (UPS).
The UPS can provide power for PLCs, HMIs, and key instruments for a duration ranging from a few minutes to over an hour, depending on boiler capacity.
During this backup power window, the control system executes a safe shutdown sequence, including:
Sequential shutdown of auxiliary equipment
Activation of emergency ventilation valves
Prevention of combustible gas accumulation in the furnace
Additionally, the UPS ensures that alarm systems and communication devices remain operational, allowing operators to receive power failure alerts in real time.
Case Study:
A customer plant once experienced a complete power failure. The UPS in Rentai’s control cabinet immediately took over, keeping the control system active long enough to safely shut down the boiler and activate emergency water circulation. By the time backup generators restored power, the boiler had already entered a safe state, preventing any hazardous incidents.
3. Mechanical and Passive Safety Devices
Beyond electronic control, Henan Rentai emphasizes last-resort mechanical safety protections:
Boilers are equipped with mechanical safety valves that automatically release pressure when it exceeds safe limits—independent of the control system.
If residual heat causes excessive pressure buildup during a power failure, these safety valves provide critical protection.
Some solid fuel boilers include gravity-based cooling mechanisms, such as natural circulation heat dissipation, which passively remove excess heat without requiring electrical control.
Rentai’s control system design fully accounts for these mechanical safeguards, ensuring integrated safety strategies that reduce reliance on electronic intervention.
Safe Restart Logic After Power Restoration
Power failures are often temporary, and once power is restored, the control system must ensure safe reactivation without unintended actions.
Henan Rentai’s PLC software includes:
Power failure memory: The PLC stores the boiler's operational state before the power outage.
Self-diagnosis upon power restoration: Before resuming operation, the system performs a safety check to verify conditions.
Manual confirmation before restart:
If the boiler was running before the power failure, the system remains in shutdown mode until an operator manually confirms a safe restart.
If the boiler was already shut down, it remains off after power restoration to prevent accidental reactivation.
Timers and logic reset: Prevents incorrect sequences caused by power interruptions during active control cycles.
These safety measures prevent unintended startups or hazardous conditions after power restoration.
Impact of Network Interruptions and Countermeasures
As boiler control systems become increasingly networked, network communication failures must also be considered. These failures can involve:
Factory-level control network interruptions (e.g., loss of connection between boilers and the DCS or SCADA system).
IoT and remote monitoring disruptions (e.g., loss of internet connectivity affecting cloud-based services).
1. Factory Control Network Failure
Henan Rentai designs its systems with a "local autonomy" principle:
Each boiler's local PLC operates independently and does not rely on external network commands for core functions.
If network signals are lost, each boiler continues operating based on its pre-configured control logic.
For boiler group control (multi-boiler coordination):
Under normal conditions, the group control system optimizes load distribution and startup/shutdown schedules.
If the network fails, each boiler automatically switches to standalone operation and maintains stable steam pressure.
Once network connectivity is restored, the system resumes centralized coordination.
For DCS connection failures, local HMI panels allow operators to continue monitoring and controlling the boiler directly, ensuring uninterrupted operation.
2. IoT and Remote Monitoring Disruptions
A loss of remote connectivity does NOT affect boiler operation—it only temporarily suspends remote monitoring and diagnostics.
Rentai’s IoT solutions use buffered data storage, meaning that when the network is restored, stored data is automatically synchronized.
On-site visual and audible alarms remain functional to notify personnel of critical conditions even if remote alerts cannot be transmitted.
To increase remote monitoring reliability, Rentai’s systems support multiple communication pathways, such as:
Wired Ethernet + 4G wireless redundancy
Automatic failover between communication channels
If all network paths fail, the boiler continues stable operation, and historical data is synchronized once connectivity is restored.
Henan Rentai's Reliability-Driven Design
To ensure robust performance under all conditions, Henan Rentai employs:
Hardware Redundancy:
Dual-PLC redundancy, redundant sensors, and triple-redundant DCS architectures for mission-critical applications.
Software Fault Tolerance:
Automated exception handling for sensor failures, command timeouts, and control interruptions.
Emergency Manual Override:
Operators can use physical emergency shutdown buttons to take manual control if needed.
Conclusion
With multi-layered safety features, Rentai’s control systems ensure continuous protection even in extreme scenarios. Whether power outages or network failures occur, Rentai’s solutions guarantee that boiler safety is never compromised.
?? Contact Henan Rentai Electric:
Phone: +86-17638563962 / +86-0371-56520104
Email: info@hnrentai.com