Steam Separator in Boiler

Steam separator has main function to separate water and steam and this equipment is usually located in steam drum. Water surface in steam drum is turbulent, so make it easy to mix between steam and water. The principle of steam separator is make steam flow is changed in any direction. Because of density of steam is lighter than water make steam can be distributed easier than water. The water droplet which has higher density will be separated and dropped from steam. Moisture will be removed by steam separator to eliminate damage and erosion if water or wet steam is distributed to the steam line.

There are some types of steam separator. For small scale steam boiler, steam separator consists of dry pipe which has a lot of holes at the top and two holes at the bottom half. The mixture steam-water is directed through the top half holes dry pipe, turbulent moving force the mixture to separate between water and steam. Steam will flow to steam line and water will drop through bottom holes (see figure 1).

Fig. 1: Dry Pipe Steam Separator
Source: Book - Boiler Operator's Exam Preparation Guide - Theodore B. Sauselein

For big scale boiler which has complexity equipment, steam separator method use centrifugal force for better result. The mixture steam-water is forced to move around the cyclone and make the rotation (see figure 2). The more turbulent moving force the mixture separate easily. 

Fig. 2: Centrifugal Steam Separator
Source: Book - Boiler Operator's Exam Preparation Guide - Theodore B. Sauselein