56 replies to this topic

[PingPong]

No, when making a design you can get any bridgewall temperature you like, irrespective of the air preheat temperature, because you simply choose it.

 

Based on air preheat temperature, fuel composition and % excess air you can use Aspen to calculate the adiabatic flame temperature T₁. Aspen will also give you flue gas properties.

Then you choose the bridgewall temperature, say T₂.

 

When your radiant duty, including some heat loss, is Q_r then you can simply calculate how much flue gas has to be cooled from T₁ to T₂ to provide Q_r 

 

You can do this for several air preheat temperatures, say 350, 400, 450 and 500 ^oC as you don't know yet what your air preheat in the convection section will be.

Edited by PingPong, 22 December 2021 - 03:46 AM.

[daraj]

Thanks. for sizing the reformer tubes, what is the typical flux used for a top-fired reformer for hydrogen production? and the dimensions of the tubes?

[PingPong]

for sizing the reformer tubes, what is the typical flux used for a top-fired reformer for hydrogen production? and the dimensions of the tubes?

You should really read all my posts in the other topic that I mentioned to you before:

 

https://www.cheresou...-reformer-unit/

[daraj]

OK,I will, thanks a lot for your inputs

[daraj]

Pingpong, the term "absorbed duty" in the contect of a fired heater/reformer, does it refer to the duty that is actually usefully utilized. i.e if 100 MW of fuel is burnt and 90% is overall efficiency, then 90MW is the absorbed duty here?

 

also do you know of any cost vs duty correlations for steam reforers? lets say i have a top fired reformer of 500 MMBtu/hr of absorbed duty(or useful duty i understandn it), then wondering what would be typical USGC installed cost?

[PingPong]

Pingpong, the term "absorbed duty" in the contect of a fired heater/reformer, does it refer to the duty that is actually usefully utilized. i.e if 100 MW of fuel is burnt and 90% is overall efficiency, then 90MW is the absorbed duty here?

The term "absorbed duty" can be used for individual coils in a reformer heater.

If you would use it for the whole heater then you need to indicate that it is excluding the air preheat coil duty as that absorbed duty does not leave the heater but is merely recycled back to the burners.

Including APH the absorbed duty of all coils together can be higher than the fired duty but that obviously is not relevant.

also do you know of any cost vs duty correlations for steam reformers? lets say i have a top fired reformer of 500 MMBtu/hr of absorbed duty(or useful duty i understand it), then wondering what would be typical USGC installed cost?

I don't have accurate and up to date cost data for SMR units.

Graphical representation of installed cost for SMR unit is usually as function of hydrogen product.

See for example this graph from the book: Petroleum Refining Technology and Economics 5th Edition - Gary, Handwerk & Kaiser 2007  which gives investment cost in 2005. You need to increase that number (using CEPCI) to obtain today's investment cost.

 

 Investment cost SMR Unit 2005 USGC.jpg   99.99KB   4 downloads

Edited by PingPong, 16 January 2022 - 05:17 AM.

[daraj]

OK, thanks