Boiler drum level control method is one thing should be considered in the operation of steam boiler. The steam drum is a crucial component of steam boiler. This vessel’s main purpose is to supply volume and area close to the top of steam boiler in which separation of steam out of water could happen. Steam drum as well gives a place for recirculation water, add-on feedwater, chemical water treatment and also boiler blowdown system which eliminates deposits and keeps a specific amount of impurity to minimize scale creation. Since these capabilities require the continuous inclusion a loss of substance, the amount of steam-water interface is crucial.
Lower level impacts the water recirculation to the tubes of steam boiler and also decreases circulation of water to the tubes as well as decreases the performance of water treatment. High level decreases the area, along with result in dissolved solids and water going into the supply system of steam. The purpose of the boiler drum level control method is to keep the interface of steam-water on the specific level plus present a constant mass/amount balance simply by changing each single pound of steam along with water eliminated with a single pound of feedwater.
The interface level is susceptible to numerous troubles, the pressure of steam becoming a significant one. When the pressure of steam changes because of need, there's transient adjust in level because of the impact of on steam bubbles which is entrained under the interface level of steam. Since pressure declines, an increase in level, known as swell, takes place mainly because the captured bubbles expand. Since pressure increases, a decrease in level happens. This is known as shrink.
There are actually 3 fundamental kinds of boiler drum level control methods as following below and their practical application will depend on the certain boiler dimensions and load alterations:
- Single element drum level control method
- Two element drum level control method
- Three element drum level control method
Boiler drum level control ideally should be equipped with alarm as signal or indicator of drum level. Too high or too low level of boiler water in steam will lead to damage and deterioration in steam boiler. Furthermore, alarm is an important device to maintain proper drum level control.