U.S.A Boiler water wall panels

Boiler Water Wall Panels

The boiler water wall panels are generally arranged around the furnace to receive the radiant heat of flame and flue gas. For double side exposed water wall, the water wall is arranged in the middle of the furnace.

1. Classification of water wall

Drum boiler: water wall is evaporation heating surface;

Once through boiler: because there is no drum, there is no obvious boundary between evaporation section and superheating section. The water wall is used outside the evaporation heating surface, and part of it is used for preheating and superheating.

2. Function of water wall

2.1. Protection of furnace wall

After the water wall is laid on the furnace wall, the temperature of the inner wall of the furnace wall decreases, the furnace wall is protected and the structure of the furnace wall is simplified.

2.2. Evaporation heating surface

Receive the high temperature radiant heat from the furnace to make the water in the tube absorb heat and evaporate

2.3. Avoid slagging

The water wall absorbs a large amount of radiant heat, reduces the temperature of flue gas, reduces the ash content in flue gas at the furnace wall below the softening temperature, and avoids slagging on the furnace wall and heating surface.

3. Structure of water wall

3.1. Smooth tube water wall

The smooth water wall is composed of smooth seamless steel pipe, which is generally arranged vertically close to the inner wall of furnace wall;

The upper end of the water wall is connected with the drum or the upper header, and the lower end is connected with the lower header.

3.2. Pin type water wall

Many cylindrical pins are welded on the outside of water wall tube to form pin type water wall. The pin can make the chrome ore Refractory firmly connected with the water wall.

Function: the surface of pin type water wall is covered with refractory material to reduce the heat absorption of water wall, so as to maintain local high temperature.

Application: it is used in the combustion belt of solid slag discharging pulverized coal boiler, slag pool of liquid slag discharging pulverized coal boiler, cyclone of cyclone furnace, etc.

3.3. Fire belt (combustion belt)

The water wall around the combustion chamber is covered with refractory materials, and the covered area is called the fire belt or combustion belt.

The purpose of the combustion belt is to increase the temperature of the combustion area and create conditions for the ignition and stable combustion of the coal which is difficult to ignite. In order to improve the temperature of the furnace, the burner area is equipped with a fire belt.

3.4. Membrane water wall

The membrane water wall is welded by finned tubes along the longitudinal direction to form an integral heating surface, which makes the furnace wall surrounded by a whole water wall membrane.

There are two types of finned tube: Rolled finned tube and welded finned tube

3.5. Slag pipe is arranged at the outlet

The water wall at the outlet of the back wall water furnace is thinned and arranged with 2-4 rows of pipes to form a flue gas channel, which is called slag condensation pipe.

The sparsely arranged water walls further cool the flue gas to make the fly ash condense into a solid state to prevent slag condensation on the tail heating surface. Under off design conditions, slag may form in the slag pipe first, which protects the tail heating surface

3.6 membrane water wall

The main advantages are as follows

3.6.1. Tightness to reduce air leakage;

3.6.2. The wall should be well protected, and the light insulation wall can be used; The boiler starts and stops quickly with less heat storage;

3.6.3. The radiant heating area is increased to save steel;

3.6.4. The membrane water wall can be prefabricated and installed in pieces to reduce the installation workload and speed up the installation progress;

3.6.5. Increase the pipe rigidity and improve the furnace explosion resistance.

4. Main specification of the pipes for the boiler water wall panels.

4.1. Main water wall pipe materils: 20G,15CrMo (15CrMoG),15Mo3,SA-210C(25MnG),SA-210A1,SA-213T12 and so on.

4.2. Main light pipe specifications:∮31.8X5,∮38X6.5,∮38x7.3,∮60×5,∮60X6,∮60X6.5,∮63.5x7.5 and so on

4.3. Main female threaded pipe specifications: ∮35X6.5,∮45X5.4MIN,∮50.8X5.59MWT,∮50.8X5.8MWT,∮51X5.7MWT,∮60×6.5,∮60X7,∮63.5X6.6MWT,∮66.7X8 and so on.

4.4. Flat steel materials: Q235-A，20，15CrMo、12Cr1MoV

4.5. List of pipes used for 660MW boiler water wall panels (for reference)