4 replies to this topic

[pghstochaj]

Hi Everybody.

First time I have seen this site but fingers crossed it will help!

I am doing the design, as part of my course, a section of a syngas (H2 + CO) production plant; naphtha vaporisation and hydrodesulphurisation.

I am started with what I considered to be the easy part of the system, the vaporiser. The first part of the project said that we would use the hot output from our reformer downstream to pre-heat and vaporise the naphtha feedstock. So I need to design a heat exchanger to heat and vaporise the naphtha using heat integration (steam on start up).

There's a big but however, I don't seem to be able to work out what type of heat exchanger all of the syngas plants seem to use and it's really getting me behind and down.

Could somebody, please, point me in the right direction and set me free to start a design?

Thanks in advance
Paul

[bushtie]

Hi Paul

I find Incropera and De Witts's Introduction to Heat Transfer a big help when designing heat exchangers. Its a popular book and has many versions now (I currently have the 4th edition).

Hope this helps

[pghstochaj]

THanks for the quick reply. I will look at it tomorrow in the library, 11 copies but 6 out; usually that means the other 5 have "gone missing". Maybe I should be more optimistic though!

I have spent 4 years of my life understanding chemical engineering and doing countless HT equations but I don't feel like it has been at all applied to what happens in industry, it's really frustrating.

I just hope that somebody can maybe suggest the normal type of exchanger utilised for such a duty and it will set me going.

THanks again
Paul

[Zauberberg]

pghstochaj,

In several refineries, I have seen huge AlfaLaval packinox heat exchangers ("Texas towers") employed as naphtha reformer feed/reactor effluent heat transfer devices. Looking at the PFD (feed flow direction), fired heater downstream of these exchangers is usually provided for required supplementary duty - speaking of refinery Naphtha HDS and Reformer units process. However, I think that vaporization of naphtha should not be your primary concern - evaporation occurs in the reactor section due to high H2 partial pressures. The duty of your exchangers is driven by the overall feed/effluent heat balance and downstream/upstream equipment capacities.

Hope this helps,

[pghstochaj]

Thanks for the reply. I spoke with my supervisor who also set me on a better line that where I was going.

Regards
Paul