Alloy Steel Superheater And Reheater For Pulverized Coal Boilers
With Natural Circulation
Description: Superheater Coil
Parameters
| Material | carbon steel, alloy steel , or durable heat steel |
| Tube OD | 10-114mm |
| Tube W.T. | 0.8mm- 15mm |
In general, steam heated in high pressure superheater is named
superheated vapour, the steam heated by reheater is called reheated
vapour. The parameter of reheated steam is relating with economy of
thermal circulation. Generally, the pressure of reheated steam is
about one fifth of that of superheated steam, and the temperature
of the former is almost the same as that of the latter. For
example, in our nation for boiler with 125MW, 400t/h, the
parmameter for superheated steam is 133.7Mpa and 555 degrees; the
inlet and outlet pressure of reheated steam is 2.5/2.35MPa, their
temperature is 555 degrees, too.
For boilers with 200MW, 670t/h, the parameter of superheated steam
is 13.7MPa, 540 degrees; the inlet and outlet pressures are
2.7/2.5Mpa, and the temperature is also 540 degrees. For
subcritical pressure control circulation boilers with 300MW, 600MW,
superheated steam parameter is 18.27Mpa, 540 degrees; the inlet and
outlet pressures are 3.83/3.63MPa, the temperature is also 540
dgrees. Application of steam reheating system can increase the
thermal economy for power stations by 4-5%. In our country, units
with capacity over 125MW all apply one time middle reheating
system, and overseas, two times middle reheating systems are
applied for some units with higher parameters.
Product Introduction: Superheater coil
Reheater is actually a kind of steam superheater which heats the
low-pressure steam after work and reaches a certain temperature.
The role of reheater further improves the thermal efficiency of the
circulation in power plant, and makes the steam temperature of the
last stage blade of steam turbine controlled within the allowable
range.
A reheater is a boiler that converts steam from a steam turbine
into superheated steam.
The reheater has two functions: one is to reduce the moisture of
water vapor, which is beneficial to protect the turbine blade;
Second, the relative and absolute internal efficiency of steam
turbine can be improved.
Details: Superheater coil
Generally 30 ~ 60 mm.The most common type of flow superheater is
serpentine tube.It has a more intensive tube group, decorate in 450
~ 1000 ℃ flue of the flue gas temperature, flue gas of vertical and
lateral erosion.The flue gas mainly transfers the heat to the pipe
by convection, and some of the heat is absorbed by radiation.The
plate-type superheater consists of a plurality of tube screens,
arranged in the upper part of the furnace or at the outlet,
belonging to the radiation or semi-radiation type superheater.The
former absorbs radiant heat from the furnace flame, while the
latter also absorbs some convection heat.In power station boilers
above 10 mpa, both screen type and serpentine type superheater are
commonly used to increase heat absorption.The wall superheater
applied on the inner wall of the furnace is radiant superheater,
which is seldom used.The wall-mounted superheater is used in the
large capacity power station boiler to form the wall of the furnace
top and convection flue.The picture shows the arrangement of
several superheater.The small capacity industrial boilers with
superheater can meet the requirements only with single stage
superheater.
The reheater layout follows the superheater layout, including
convection, radiation and semi-radiation.
The convection reheater has reverse flow, downstream flow and mixed
flow, single coil, double coil, multi-coil, parallel and staggered,
vertical and horizontal type, parallel to the front wall and
perpendicular to the front wall.Convection reheater is the main
reheater that absorbs convection heat.
Radiant reheater refers to the reheater absorbing furnace
radiation.
Semi-radiant reheaters (plate superheater) refer to reheaters that
absorb more radiation from the furnace (more than 1/2 of the total
heat).
The material selection principle of reheater is the same as that of
superheater. Since reheating steam is inferior to superheater in
cooling capacity, the design wall temperature is generally higher
than that of superheater of the same temperature level.Metal tubes
of high temperature reheaters are generally made of alloy steel
(metal tubes containing more than 5% of alloy elements).For
example, 12CrlMoV, steel 102, sa213-t91, sa213-tp304, sa213-tp347,
etc.
Qur Company
Hua Dong Boiler has become a major qualified supplier of domestic
and foreign boiler manufacturers and energy companies, including
American Covanta Energy Company, AMEC Foster Wheeler Company,
ALSTOM, Oriental Boiler Limited by Share Ltd., Harbin electric LLC,
Wuxi Hua Guang Boiler Co., Ltd., Hangzhou Boiler Group Co., Ltd.
