Supercritical Boiler
1. Operating Pressure > 225 Kg/Cm2, It Is Called A Supercritical Boiler.
2. The Most Techno-Economical Parameters For Supercritical Plants Envisaged Are:
Main steam Pressure | @ SH outlet is 250 Kg/Cm |
540 Deg.C | Main Steam Temperature At Sh O/L. |
566 Deg.C | Hrh Temperature At Rh O/L. |
3. Improvement In Cycle Efficiency for above Parameters Is Of The Order Of 3%.
4. There Are Two Types Of Water Walls Arrangements In The Case Of Once Through Boiler:
A) Spiral Wound WW.
B) Vertical Ribbed WW.
5. Most Of The Once Through Boilers In The World Are With Spiral Wound WW. This Arrangement Has The Advantage Of Equal Heat Absorption By All The Steam Generating Tubes.
The Disadvantage Of This Arrangement Is That The Tubes Are Not Self-Supporting. Hence, Extra Supports Are Provided To WW For This Arrangement.
Typical Materials Used For Super critical Boiler
Elements Of Boiler | Material |
Economizer | Carbon Steel |
Water Wall | Low Alloy Ferritic Steel |
Pressure Vessels (Separator, Drain Tank) | Low Alloy Ferritic Steel |
Sh Tubes (Heating Area) | Austenitic Steel (Tp347h / Tp321h) |
Sh Tubes (Non-Heating Area) | Medium Alloy Steel (T91) |
Main Steam Pipe | Medium Alloy Steel (P91) |
HRH Pipe | Medium Alloy Steel (Scmv28) |