Boiler Low Water Level

1. Typical Symptoms

- The water level in the water level gauge is below the lowest mark (“water level not visible”); in severe cases, the glass tube of the water level gauge turns white (no water mark);

- A sharp rise in boiler tube temperature (due to lack of cooling water, resulting in overheated tube walls), followed by a rise and then a drop in steam pressure (later stages show no steam-water circulation, leading to reduced output).

2. Root Causes

- Feedwater system failure (feedwater pump trip, feedwater pipe leak);

- Blowdown valves left open or leaking (continuous blowdown valve opened too wide, or periodic blowdown valve left open);

- False water level in the water level gauge (piping blockage; the displayed water level appears normal but there is actually a water shortage).

3. Response Procedures (Never add water blindly to prevent boiler tube rupture)

1. Emergency shutdown: Immediately stop fuel supply, shut down the forced draft and induced draft fans, and under no circumstances add water to the boiler (superheated boiler tubes will rupture instantly upon contact with cold water);

2. Determine the severity of the low-water condition: After the boiler has cooled (when the furnace tube temperature drops below 200°C), open the water level gauge drain valve, then slowly open the feedwater valve. If a water level appears in the gauge, the low-water condition is minor; if no water level is visible, the condition is severe (inspect the furnace tubes for deformation);

3. Repair the fault: Inspect the feedwater system for leaks and check the condition of the blowdown valves; replace any faulty feedwater pumps or repair the valves;

4. Replenish water and resume operation: If the water shortage is minor and the furnace tubes are undamaged, slowly add water to the boiler until the normal water level is reached, then follow the procedure to increase temperature and pressure; in cases of severe water shortage, inspect the furnace tubes first and replenish water only after they have been verified to be in good condition.