ASME or CE Standard Seamless Carbon Steel Superheater for 75 T/H
Lignite Fired CFB Boiler
Arrnagement and specification:
The boiler has high and low superheaters, the HS is arranged in the
flue gas duct after cyclone separators, and the LS is arranged in
back-end vertical shaft. The saturated steam is introduced into the
ceiling enclosure headers by eight φ108×5 saturated steam
connecting tubes on the drum, and then into the lower temperature
superheater through φ 42×4.0 tubes, after being heated by LS, goes
into desuperheater for adjusting temperature, and then goes into HS
through eight tubes of φ108×5, and sent to steam turbine through
main steam valve after going into SH outlet header.
The LT superheater adopts contranatant arrangement and the HT
superheater is downstream arrangement. The collection and
distribution of steam adopts the way of width direction to improve
non-uniformity of steam flowing and prevent local coils superheated
due to steam deflection.
To ensure safety operation, the LT superheater uses SA210 Gr.A1
seamless steel tubes, and the HT superheater uses low-alloyed SA213
T22 seamless steel tubes.
Superheater is the part that heats the steam from the saturation
temperature to the superheater by the boiler. It is also called the
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
They all consist of a number of parallel pipes and inlet and outlet
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
The accessory of high temperature radiant steam super heater in
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?
|Pendant-type||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|
|Inverted-type||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