ASME Standard SA192M Membrane Boiler Water Wall Power Plant Boiler Tubes

ASME Standard Boiler Membrane Walls Made of SA192M for Replacement/Maintenance of Sugur Mill

Product Introduction

Water wall panels are the main heating surface of boilers, composed of numbers of rows of steel tubes, arranged around the boiler corner. Inside is the flowing water or steam, and the outside accepts the heat of the flame in the furnace of the boiler, mainly absorbing the radiation heat of the high temperature combustion products in the furnace. The working fluid rises in it and evaporates by heat.

When the water wall was initially designed, it was not intended to be heated, but to cool the furnace so that it would not be damaged by high temperature.Afterwards, because of its good heat exchange function, gradually replacing the steam drum to be the main heating parts for boilers. They are the evaporative heating surface consisting of many parallel tubes laid on the inner wall of boiler hearth. Their functions are to absorb the radiant heat by high temperature fire or gas flue in the furnace, and produce steam or hot water inside the tubes, and also reduce the furnace wall temperature so as to protect it. In large capacity boilers, the flame temperature in the furnace is very high and the intensity of heat radiation is very high. 40-50% even more of heat is absorbed by the water wall.Except small capacity boilers, the main evaporative heating surface for the present water tube boilers are the water wall.

If according to the structure type, water walls can be divided into types: bare tube type, membrane type and prick tube type.

Membrane type is the most widely used one.

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.

According to the different manufacturing process, the membrane water wall can be divided into three types(see Fig. 1):1.rolled fin tubes are welded in rows, with less welding workload, but the fin tubes are expensive. 2.bare tube and fin(flat steel) are welded in rows, which has low material cost and can easily meet the requirements of various pitches, but flat steel requires high precision and finishing equipment.3.Bare tube fusion welding,the fins between tubes are formed by filling the welding wire, mostly used for the small pitch between the tubes. The pitch between tubes of membrane water wall is related to factors such as boiler pressure and furnace heat load, usually s/d is 1.2-1.5.

Specification

The pictures above are membrane walls for one Pakistan project with details of specification below: