Tube Supports Temperature Design of Fired Heaters

[Wrl69]

We have to modify convection section in two fired heaters (oil refinery), to obtain a determined (by customer) outlet fuel gas temperature. So we have the following questions:

1. On their condictions, the shield section tube supports temperature design will be 2098°F; it is over API 560 indication (2000°F). What can we do? What material of tube supports is recomended on that temperature?

2. What can we do, if flue gas temperature gradient across a single convection intermediate tube support is over 400°F, indicated by API 560? In our case we have one case with 844°F and other case with 506°F.

Thanks,

 

[scsekhar]

WRL69,
One way of getting over the temperature gradient limitation would be to simply split the intermediate tube sheet at the point where the temperature gradient is about 400F or less. The detailing could get a bit tricky but by leaving the top row of tube holes open ended, we could achieve this.

One could think of Incoalloy 800H or 50Cr-50Ni castings for the high temperature zones.

S.C.Sekhar

 

[ijzer]

For 2098 Deg. F you could used HP40Nb (0.4C/25Cr/35Ni/Nb)
Alloy 800H and 50/50 are not suitable.