Features water circulation drum boilers
design feature steam drum boilers is the presence of the drum - tank, through which creates a movement of water in a closed hydraulic system.Inside the drum are perforated separation device and feeder tube.
Water flowing pre-chemical water treatment and de-aeration is supplied to the economizer of the boiler, where it is heated by the heat of exhaust gases.Then it gets to the top of the boiler drum.As a standpipe of the water goes to the sewer system, and the rest - in the lower drum.
By heating heat of the combustion products, the water
turns to steam-water mixture and returned to the upper drum.There passing through the separation unit, the steam is separated from water and fed to the consumer.Evaporable water is returned to the circulation circuit. multiplicity of circulation - the ratio of water passing through the circuit per unit time to the amount of steam produced during the same period.For once-through boilers it is always equal to 1, and for the drum varies from 5 to 50.
In once-through boiler drum there.Pre-prepared water under the influence of the feed pump passes through the economizer to the evaporator tubes, which completely transformed into steam.
Zone, which ends the process of vaporization is called transition.Next, steam enters the superheater where it is heated to a predetermined temperature and is sent to consumers.Once-through boilers are open-loop hydraulic system. ramjet called boiler with forced movement of water without circulation.Lack of water in the evaporator surface allows them to work on the subcritical and supercritical pressures.
Pros and cons of direct-flow boilers
Compared drum and straight-through boilers, the main advantage of the latter will prompt inclusion in the work and the minimum time required for heating the water.Because of this, once-through boilers can be used as back-up facilities during loading of the main equipment.Another significant advantage is the compactness of the (lack of drums and collectors) and maneuverability.
Unfortunately, the lack of storage reservoirs leads to frequent enable or disable the burner.As a result, there is a premature wear and increased fuel consumption.