Flame Detection and Shutdown Interlock Protection Device

The core principle of the flame detection and extinguishing interlock protection device is to monitor the flame status in real time. Upon detecting the extinction of the flame, it immediately triggers the preset interlock action to cut off fuel supply and prevent the accumulation of fuel from causing safety accidents.

The device is essentially a closed-loop control system of "monitor - judge - execute," primarily achieving protection through three core stages.

Flame Signal Collection (Monitoring Phase)

This phase is handled by the flame detector, which is responsible for converting the physical presence of flames into identifiable electrical signals.

The device will be equipped with specific types of flame detectors, commonly including ionization, ultraviolet (UV) photometric, and infrared (IR) photometric types.

The detector continuously monitors the flame within the burner or furnace. If a flame is present, it outputs a stable detection signal (such as ion current, photoelectric signal). If the flame extinguishes, the signal will immediately disappear or drop below the set minimum threshold.

Signal Analysis and Logical Judgment (Judgment Phase)

This phase is handled by control units (such as PLCs, dedicated controllers), responsible for processing and making decisions on the collected signals.

The control unit amplifies, filters, and compares the signals received from the detector.

The processed signal is compared with the predefined "Fire/No Fire" thresholds to determine if the current flame is in a normal state.

Some devices will be equipped with a "time-delayed judgment" function to prevent false operation caused by sudden fluctuations in flame (such as brief extinguishing due to air flow disturbances). The time delay is typically adjustable according to operating conditions (e.g., 1-3 seconds).

3. Interlock Action Execution (Execution Phase)

This phase is handled by the execution agency, responsible for converting the control unit's decisions into actual safety operations.

Once the control unit determines "fire extinguished," it immediately sends instructions to the executing unit.

Upon receiving the command, the executive machinery acts swiftly, with core actions including cutting off fuel supply (such as closing the fuel valve) and, in certain scenarios, activating the blow-off device (using inert gas or air to clear residual fuel in the furnace) and triggering audible and visual alarms.

After the fault is resolved and manually confirmed safe, the interlock must be disengaged through a reset operation to restart the combustion system.

Core Components and Features

The stable operation of the equipment relies on the coordinated work of its components. The key components and their functions are as shown in the table below: