6.1 Water Columns

Maintaining the correct water level in a boiler at all times is the responsibility of the boiler operator. Gauge glasses are provided for assistance and are installed to indicate the level of water in the boiler or boiler drum.

Drum water level is one of the most important measurements for safe and reliable boiler operation. If the level is too high, water can flow into the superheater, and subsequently, waterdroplets could be carried into the turbine. These waterdroplets will leave deposits in the superheater and possibly cause tube failure, and any waterdroplets carried to the turbine will cause serious erosion problems on the blades, resulting in high maintenance costs as well as costly outages. The results from too low of a water level are more severe, since this would result in a reduction in the water circulation and this could cause the tubes to overheat and ultimately fail, causing costly maintenance and repairs and potential injury to personnel.

For the small low-pressure boiler (Figs. 6.1 and 6.2), the gauge glass is attached directly to the drum or shell by screwed connections, or a water column may be used. The water column is a vessel to which the gauge glass or other water-level-indicating devices are attached. (Refer to Fig. 6.3). The water column permits the gauge glass to be located where it can be seen easily and makes the installation accessible for inspection and repairs. The location of the gauge glass and water column varies for different types...