would you please explain combustion nozzles that which one is primary and which is transfer or secondary nozzles? (with figures please)

 

you don't have a manual from GE or the GT manufacturer?

 

Ali,

If the turbine was provided by GE or one of its licensed packagers there should be a manual provided with the unit which has several distinct sections. One of them includes written system descriptions for each one of the systems, and it seems from your post the turbine in question has DLN-I combustors and most probably burns natural gas, and possibly liquid fuel (you didn't tell us what fuel(s) is(are) burned in the turbine).

You should be able to go the System Description for each fuel and find some very good information about system operation, components, and flow paths.

Unfortunately, we can't post figures or drawings on control.com that would be of much help in this particular case (and, again, we don't know how many fuels are burned in the turbine at your site).

GE is EXTREMLY protective of its technology and IP (Intellectual Property) these days, and if anyone were to post GE drawings to any Internet hosting site they would most likely receive a 'cease and desist' letter (at a minimum) from GE. So, we can't just scan and post GE drawings to the Internet for review.

If you can't get access to the manuals provided with the turbine (and I know some sites restrict access to the manuals to supervision and management only--which is a shameful practice) but you still have questions, please try to ask them here and we will do our best to help you. It's very difficult to "draw" in ASCII text, but we'll try to help as best we can.

It would help us to help you if you would tell us about any issues which might be prompting this question (exhaust temperature spreads; primary zone re-ignitions; failures to transfer combustion modes; etc.). The more information you can provide about specific questions or issues the better information we can provide--and faster.

However, again, it's not possible to post figures and drawings to control.com, or to refer you to any figures or drawings other than what you should be able to find in the manuals provided with the turbine(s) at your site--which should always be consulted first.

 

Ali,

It's important to note that each of the figures in this post are CROSS-SECTIONAL SIDE VIEWS of the components listed. It's very difficult to draw figures for posting to control.com, so you're going to have to visualize lines that can't be drawn using ASCII text characters for openings in the ends of the primary fuel nozzle body, the combustion liner and the secondary fuel nozzle body (at the left of the components). An effort was made to show the Primary Fuel Nozzle Body (again, from the side in a cross-sectional view), the Secondary Fuel Nozzle Body (with the Secondary- and Transfer gas passages and nozzles/orifices), the DLN-I combustion liner with the venturi that separates the Primary- and Secondary Combustion zones, and the complete combustor assembly.
<pre> Primary Fuel Nozzle Body
Cross-Section
--------------------------
__
| |
| |
| |
| |
|--------
Primary---> | <---Primary
Fuel | ------ Fuel Nozzle/Orifices
Gas | |
| |
|__|

Opening in Center of
Primary Fuel Nozzle Body
for Seconday Fuel
Nozzle Body

__
| |
| |
| |
| ------ Primary
| | <---Fuel Nozzle/Orifices
|--------
| |
| |
| |
|__| </pre>
The primary fuel nozzle body is a very large circular piece of steel that bolts on to the end of a combustor. It contains multiple (five, if I remember correctly) primary fuel nozzles arranged in a circle which protrude through openings in the combustion liner inside the combustor. For a GE-design Frame 9EA heavy duty gas turbine, there are 14 combustor, so there are 14 primary fuel nozzle bodies, each with multiple primary fuel nozzles. (If my memory is correct and there are five primary fuel nozzles per combustor, then there are 70 primary fuel nozzles for a Frame 9EA.) There is an internal passage in each of the primary fuel nozzle bodies that connects the gas fuel input port on the primary nozzle body to the primary fuel nozzles. There is a hole in the center of each primary fuel nozzle body through which the secondary fuel nozzle body passes.
<pre> Seconday Fuel Nozzle Body Cross-Section
-----------------------------------------

+
+ + _ <---Secondary Fuel "Pegs" with Orifice(s)
+_++++++++++++++++++| |+++++++++++++++++++
Secondary Gas---> | <---Secondary Nozzle Orifices
+-----------------------------------------
Transfer Gas---> | <---Transfer Nozzle/Orifice
+-----------------------------------------
+ + | <---Secondary Nozzle Orifices
+ ++++++++++++++++++ +++++++++++++++++++
+ |_|
<---Secondary Fuel "Pegs" with Orifice(s)</pre>
The secondary fuel nozzle body is basically a long "tube" that bolts onto the center of the primary fuel nozzle body and protrudes through a "barrel" in the middle of the combustion liner. Each secondary fuel nozzle body has two separate internal passages: one for the secondary fuel nozzles and and one for the transfer fuel nozzle. If my memory is correct, the transfer fuel gas nozzle is in the center of the tip of the secondary fuel nozzle body, and the majority of the secondary fuel nozzle orifices are arranged around the transfer nozzle. Along the body of the secondary fuel nozzle are several "pegs" with orifices through which a portion of the fuel flowing into the secondary passage of the secondary fuel nozzle body exits when fuel is flowing through the secondary passages of the secondary fuel nozzle body.

Fuel does not flow through the secondary fuel passages and orifices during Primary Combustion Mode. Fuel is directed between the primary fuel nozzles and the secondary fuel passages and orifices by the Gas Fuel Splitter Valve. The Splitter Valve is an infinitely-positionable control valve which can direct all or a portion of the total fuel flow to either the primary- or secondary fuel nozzle bodies.

The transfer fuel nozzle is at the tip of the secondary fuel nozzle body and direct all of its flow into the secondary combustion zone of the combustion liner. There is only gas fuel flowing through the transfer gas passages during a Lean-Lean-to-Premix Combustion Mode Transfer as the turbine is being loaded. At all other times, purge air is flowing through the transfer gas passages to cool the passages and to prevent hot combustion gases from flowing back into the transfer gas manifold. During the Lean-Lean-to-Premix Combustion Mode Transfer when all of the gas fuel flow is being directed to the secondary gas fuel nozzle bodies, the Gas Fuel Transfer Valve takes a portion of the fuel directed to the secondary fuel nozzle body and sends it to the transfer nozzle of the secondary fuel gas nozzle body. This is done because all of the fuel required to maintain steady load during the combustion mode transfer can't flow through the secondary fuel nozzles and orifices, and to reduce combustion dynamics in the secondary combustion zone.
<pre> Combustion Liner Cross-Section
--------------------------------

Combustion Liner
Venturi

****************** *******************
* * *
* * *
Opening for **
Primary Fuel
Nozzles
*
**********************************



Combustion Liner
Center Body Opening
(For Secondary/Transfer
Nozzle)



**********************************
*
Opening for
Primary Fuel
Nozzles **
* * *
* * *
******************* *******************
^ ^
| |
Primary Combustion Secondary Combustion
Zone Zone</pre>
When trying to understand DLN-I fuel nozzles, it's important to understand the DLN-I combustor and fundamentals. The basic fundamental of DLN combustion (I or 2.nx) is to reduce the temperature of the "flame" to reduce the formation of oxides of Nitrogen (NOx). This is done by "premixing" the fuel, which is GE's way of saying "extremely lean air-fuel mixture". So, in premix combustion the ratio of air-to-fuel is very high, high enough to border on the limit of combustion stability. Premix combustion is NOT the same as "diffusion" combustion, which has the red-orange flame usually observed when burning hydrocarbon-based fuels, and does not emit the typical UV (ultra-violet) radiation spectrum as diffusion combustion.
<pre> Complete Combustor Cross-Section
----------------------------------
Combustor
__ _________________________________________________ {--- Outer
| | "Can"
| | ****************** **********************
| | *| * *
| | * * *
|-------- **
Primary---> | <---Primary
Fuel | ------ Fuel Nozzle/Orifices
Gas | | *
+ | | **********************************
+ +| | _
+_++++++++++++++++++| |+++++++++++++++++++
Secondary Gas---> | <---Secondary Nozzle Orifices
+-----------------------------------------
Transfer Gas---> | <---Transfer Orifice
+-----------------------------------------
+ + | <---Secondary Nozzle Orifices
+ ++++++++++++++++++ +++++++++++++++++++
+ | | |_|
| |
| | **********************************
| | *
| ------ Primary
| | <---Fuel Nozzle/Orifices
|-------- **
| | * * *
| | * * *
| | ******************* ********************* Combustor
|__|_________________________________________________ {--- Outer
"Can"</pre>
Hope this helps!

 

>>>!!!CORRECTION!!!<<<

I've been told Frame 9EA DLN-I combustors have six (6) primary fuel nozzles per combustor (per primary fuel nozzle body), for a total of 84 primary fuel nozzles per turbine.