Carbon Steel/Stainless Steel Boiler Parts Boiler Water Wall Panel for CFB Boilers

Introduction

The full name is water wall tube, old name is water-cooled wall,also called riser. Usually laid vertically on the inner wall of the furnace, they are used to absorb the radiant heat by the flame and high temperature flue gas.They are the main form of heating surfaces for the various modern boilers, also the basic parts of water circulation circuit. For they have the functions of cooling and protecting the furnace wall, so called water wall panels.

Membrane Water Wall

Membrane water wall is an air-tight structure consisting of pipes and fins.The advantages are less air leakage in furnace; can use pipe-laying wall, less load on steel structure and lower cost of boiler; easy to use suspension structure and improve thermal expansion system, suitable for large-scale mechanized production, high assembly rate, low heat storage capacity and shorten star-up and shutdown time. The disadvantage is that the manufacturing process is complex. Membrane water wall is often used in large capacity, high temperature and high pressure boilers.

Specification

The main function of water wall panels in boiler is to absorb the heat generated by high temperature flame or flue and to generate steam or hot water in tubes, hence to reduce the temperature in the chamber .

Material and pipe diameter for medium, high and ultra-high pressure boilers, under normal water circulation conditions, pipe wall can be well cooled, carbon steel pipe can be selected. For sub critical and super critical pressure boilers, doe to the deterioration of heat transfer and the high medium temperature(especially when the super critical parameters are reached), it is often necessary to use internal threaded tubes(multi-head spiral grooves on the inner wall of the tube, the typical structure shown in Fig. 2) or Cr-Mo alloy steel tubes. For membrane water wall, the max. Temperature and stress of fins should also be checked. The outer diameter of water wall tubes of natural circulation boiler is generally 42-76mm, the sub-critical pressure controlled circulation boilers are 42-51mm, and the once-through boilers are 22-42mm.

Strong points of membrane water wall

(1) Ensure the sealing of furnace wall and reduce air leakage in combustion chamber.

(2)The realization of full water cooling in combustion chamber is beneficial to prevent coking under the condition of intensified combustion.

(3)The cooling time of start-up and shutdown of boilers can be shortened because of its small heat storage capacity, fast temperature rise and fast cooling in combustion chamber.

(4)Pipe-laying furnace wall is suitable, which greatly reduces the load of boiler frame and it is convenient for suspension and lifting.

(5)Compared with the bare tube type, the heat absorption capacity of the tube is improved.

(6)It improves the per-assembly degree of boiler components, facilitates and reduces the installation workload.