7 replies to this topic

Hi,

For my university project i need to design a waste heat boiler, From preliminary work there is no temperature change across our waste heat boiler, only a phase change essentially (from liquid to gas) and therefore other than a rather large enthalpy change the molar flor rate, pressure and temperature remain the same - is this possible? Or must there always be a temperature change?

Any help guidance would be greatly appreciated,

Many thanks

Hannah

xxx

[pavanayi]

Hannah,
in a boiler, water gets converted to steam. If you have 10 tonnes per hour of water going into the boiler, you should get 10 tonnes per hour of steam. Also, in a boiler, the liquid absorbs latent heat of vaporisation to form vapour. So ideally there should not be any temperature change. What is confusing you in this regard? Are you reading off a stream in a simulation?

If your water stream into the boiler is not saturated, first it should be heated upto the saturated temperature (at the pressure inside your boiler), which is called sensible heat.

The outlet stream of your boiler will have the same molar flow rate and pressure (and ideally temperature) as your inlet stream, but its enthalpy and volumetric flow rate will change.
Which part did you not understand?

[srfish]

There are various types of waste heat boilers. What type are you supposed to design? The simpliest type would be a kettle reboiler where any preheating or superheating would be done externally.

Many thanks for your reply Pavanayi, it was most helpful - and cleared up my silly confusion.

Srfish - i am unsure as of yet, either a water tube or fire tube boiler, (this waste heat boiler will be used in a hydrogen production plant)

I am unsure where to begin with my design calculations and at the moment am reading Coulson and Richardson vol. 6 and Process heat transfer Kern - is there any other material you could suggest? - essentially as a starting point. Any guidance would be most useful

Many Thanks

Hannah

x

[breizh]

Consider this resource ,it might help you
http://www1.eere.ene...msourcebook.pdf

Breizh

many thanks

[mayra ahmad]

guide me too regarding the same topic from whre i get to know how to design tube end plates....

[Boeid]

Hannah,

You may try this as well for initial reference:

http://vganapathy.tr...om/boilers.html