kyong
Mechanical
- Aug 15, 2001
- 73
I'm designing a boiler steam drum/evaporator.
Problem is temperature. Flue gas design temperature is 685 C(1265 F).
Flue gas flows thorough the tubes in the drum.
Tubesheet(or called head) is also exposed to flue gas.
Tubes material is SA192 and tubesheet material is sa516-70N.
Both materials are known as having graphitization at higher than 800~850 F. Of course, because one side of the tube or tubesheet is contacted with water(457 F), the mean metal temperature is lower than 1265 F. But surface of the metal should be almost 1265 F, and mean metal temperature is 861 F.
In this case, are the materials allowed to be used? Or would the lifetime of the boiler unreasonably short due to graphitization?
Problem is temperature. Flue gas design temperature is 685 C(1265 F).
Flue gas flows thorough the tubes in the drum.
Tubesheet(or called head) is also exposed to flue gas.
Tubes material is SA192 and tubesheet material is sa516-70N.
Both materials are known as having graphitization at higher than 800~850 F. Of course, because one side of the tube or tubesheet is contacted with water(457 F), the mean metal temperature is lower than 1265 F. But surface of the metal should be almost 1265 F, and mean metal temperature is 861 F.
In this case, are the materials allowed to be used? Or would the lifetime of the boiler unreasonably short due to graphitization?