Carbon Steel Boiler Superheater for Coal- Fired CFB Boiler in ASME Standard
Superheater is the part that heats the steam from the saturation temperature to the superheater by the boiler. It is also called the superheater.
Superheater can be divided into convection type, radiant type and semi-radiant type according to heat transfer mode;
According to the characteristics of the structure, it can be divided into serpentine tube type, screen type, wall type and wall type.
They all consist of a number of parallel pipes and inlet and outlet manifold.
Most industrial boilers do not have superheaters because many industrial processes and utilities require only saturated steam.
Superheaters are generally installed in power stations, locomotives and Marine boilers to improve the thermal efficiency of the entire steam power plant.
Super heater types:
1. Radiant super heater: it is the earliest type of super heater and it is located above or behind banks of water tubes to protection them from direct flam or fire.
Parameters that increases the convection
a. Increasing the fuel-and air flow (combustion gas flow)
b. Increasing the mass flow rate of the steam
Radiation is mainly dependent on the flam temperature. as the steam flow rate increases the exit temperature become lower.
Radiant super heater
They are placed exposed to the heat source whcih requires the improvement of metal temperatures.
Radiant and convetive super heaters and reheaters are used for high temperature steam.
The accessory of high temperature radiant steam super heater in boiler
It is made up of snake-like tubes (carbon steel, alloy steel or heat-resistant steel, etc.) and collection boxes and other supporting material. Tubes generally have φ32, φ38, φ42 or other types of specifications, according to user's needs separately.
They are the sane as the super heaters but as their exit temperature is a little bit less than super heaters and their pressure is 20% -25% less than the super heater, they can stand less quality material alloys.
Steam super heater is consisted of dense tube coils and is placed in the flue under the tempearture 450ºC-1000ºC.
For power plant boiler capacity over 10Mpa, platen and coiled superheater are usually adopted.
What are the differences of Superheater And Reheater?
||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.