SA213 T91 alloy steel tube for boiler superheater and reheater tube coils rankine cycle
Alloy steel tube for boiler superheater and reheater Function
1. Modern boilers equipped with reheater pipes, specially designed so that the reheated steam absorb heat just like the main steam.
2. The reheated steam, also called hot heat reheat steam, will reach the same temperature as the main steam vapor. To achieve this, the reheater pipes will be placed not far from the final pipes of the superheater.
3. More specifically, let us refer to the following supercritical boiler diagram.
1. The Rankine Cycle equipped with a reheater, will have at least two levels of steam turbine: high pressure turbine and low pressure turbine.
2. High pressure steam turbine output steam, commonly known as cold reheat steam, has lower pressure and temperature of main steam, before entering the turbine.
3. Although the cold reheat pressure is drop significantly, it still has not reached its saturation point. So, if this steam reheated, it will return to superheated steam. Therefore the cold reheat steam that exits the high pressure turbine, will be reheated back into the boiler.
Reheater Type & Characteristics
1. The diameter of the tube is generally 30-60 mm. It has a relatively dense pipe group, which is arranged in flue gas temperature 450 - 1000 C, and is scoured horizontally and vertically by flue gas.
2. The flue gas mainly convects heat to the pipe, and some radiation absorbs heat. The former absorbs the radiation heat of the furnace flame, while the latter absorbs part of the convective heat.
3. In power plant boilers above 10 MPa, both screen and serpentine tube superheaters are usually used to increase heat absorption.
4. The wall superheater applied on the inner wall of the furnace is radiation superheater, which is seldom used. The wall-enclosed superheater is used to form the top of the furnace and the wall of the convective flue duct in a large-capacity power plant boiler.
5. The light furnace wall is made of insulating material. The picture shows the arrangement of several superheaters. Small capacity industrial boilers equipped with superheaters usually use convective superheaters of single-stage tubes to meet the requirements.
1.Firm structural support
1. Flow blockage by condensed steam 2. Needs slow restart to purge the water that accumulates in the bottom.
supported from above
1.Proper drainage of the condensed steam
1. Lack the structural rigidity, especially in high speed gas flow
Supported from below
1. Proper drainage
2. Good structural rigidity.
1. They do not view the flam directly so they are mainly from the convective type
Usually supported in the vertical gas ducts parallel to the main furnace.