×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

premix and diffusion
2

premix and diffusion

premix and diffusion

(OP)
I like to learn about the premix and diffusion mode for turbine fuel and some how more in detail, as well about the type of combustion chambers. any information or address would be appriciated.

RE: premix and diffusion

go to the particular OEM you are interested in... there is plenty of information in each website.

in a nutshell...
difussion is when the fuel is burned as soon as it leaves the fuel nozzle and more air is mixed in as it progresses along the combustion chamber, thus difussing into the products of combustion.

premix: when the fuel and air is mixed in a region of the combustion chamber and flame starts "separated" from the fuel nozzle itself.

saludos.
a.

RE: premix and diffusion

(OP)
thank abeltio. but i don't know about OEM. and how can i enter it.

RE: premix and diffusion

OEM means
Original
Equipment
Manufacturer

for example: GE, Westinghouse, Hitachi, Siemens, ABB... etc

saludos.
a.

RE: premix and diffusion


Briefly, in conventional (diffusion flame) combustors, as saludos says, the fuel/air mixture in the primary zone, where the fuel is burnt, is heterogeneous or stratified. Therefore the fuel/air ratio varies a great deal from lean to near stoichiometric. Thus high flame temperatures result in the regions where the fuel/air ratio is near stoichiometric, i.e. equivalence ratio, which is the fuel/air ratio to the stoichiometric fuel/air ratio, is nearly unity. This results in high flame temperatures, hence NOx emissions. In premixed systems, we thoroughly mix the fuel and air prior to combustion such that the equivalence ratio is in any part of the fuel air mixture never greater than 0.6. This results in low flame temperatures and therefore NOx emissions.

To achieve all this in a single stage of combustion is difficult because at low loads the equivalence ratio will decrease below the weak/lean extinction limit and the engine will flame out, particularly in aero derived gas turbines or gas turbines operating with a free power turbine. We therefore split the combustion process into two or more parts (staged combustion) and vary the fuel flow to each of these stages in a controlled manner as the load is reduced. These types of combustion systems are often referred to dry low emissions or NOx combustion systems (DLE/DLN). You can learn more about such gas turbine combustion system and gas turbine combustion is general by reading Gas Turbine Combustion by Lefebvre.

Regards,
gtsim

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources