Boiler membrane waterwall

What is boiler membrane water wall panel?

 

Membrane water wall panel is an important part of boiler heating surface. It is made of some parallel tubes and placed on furnace inner wall to absorb radiant heat from combustion chamber.

 

Water in liquid form flowing inside water wall tubes is heated and turns into saturated steam and rises up into steam drum, and water inside steam drum goes to mum drum/bottom header through downcomer. This forms natural circulation of heat transfer medium.

 

Evaporation of water cools down temperature to provide a protection for furnace wall. And lower wall temperature means less slag formation. Large capacity boiler has very high flame temperature, about 40-50% of radiant heat or more is absorbed by water wall panel, which is major heating surface for water evaporation for water tube boiler.

 

Top side of water wall panel is connected to steam drum directly or through header, while downside is connected to mud drum/bottom header. That’s why water wall panel is also named riser.

 

Boiler water wall types

 

Water wall could be classified into bare tube type, studded tube type, ribbed tube type or  membrane water wall by structure, and single side heated panel (embedded in furnace wall) or double side heated panel (placed in middle of combustion chamber) by location.

 

Bare tube water wall is composed by a row of parallel seamless tubes. It has the simplest structure.

 

Studded tube water wall is welded with studded tube and covered with refractory materials. It could build refractory belt around coal burner to suppress ignition delay and enhance combustion stability for low volatile anthracite and lean coal. Or, it is used in wet bottom boiler or cyclone boiler.

 

Ribbed tube water wall is used for once-through boiler, subcritical & supercritical boiler, high thermal load area or high evaporation ratio area of natural circulation boiler. When water flows inside ribbed tube, it creates strong turbulence to prevent film boiling, which would cause heat transfer deterioration.

 

Membrane water wall panel is a series of tubes welded together with flat steel bars. For medium & high & untra-high pressure boiler, steel material 20G is a common choice to fabricate membrane wall.

 

 

Advantages of membrane water wall panel

 

1. Gas tight enclosure reduces air leakage into boiler furnace to improve combustion.
2. Due to the biggest heat transfer surface, membrane panel gives the best protection for furnace wall, which will need only insulation and casing outside. Refractory layer is not more required. Heat storage capacity of furnace wall is minimized to shorten startup and shutdown time. Simplified, top-supported wall structure reduces metal usage and installation work.
3. Less slag formation on furnace wall.
4. Pre-fabricated unit at factory, easy installation at site.

 

Geckokintech provides OEM service for boiler parts like steam drum header, superheater, economizer, air preheater, water wall panel, etc. We can fabricate according to drawing.