Diesel engine for Frame 5

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Thread Starter

markvguy

I need an explanation or any document for gas turbine Frame 5 (john brown engineering), starting means is diesel engine, this gas turbine was controlled by Speedtronic MarkII upgraded to Speedtronic Mark VI, especially the behaviour of a diesel engine from the control side.
 
markvguy? I don't think the original control.com markvguy would be asking a question like this; he usually answered these kinds of questions.

There should be, in the original Instruction Manuals provided with the unit by John Brown, a description of the Starting Means system which should help with your understanding.

You should also have a drawing, sometimes called a Schematic Piping Diagram, or Piping Schematic, also sometimes called a P&ID, or Piping & Instrumentation Diagram, for the Starting Means systems. Regardless of what it's called, the drawing depicts the various elements of the diesel engine, clutch, hydraulic ratchet, and torque converter that make up the starting means system. It's important to have this drawing to refer to, and to become familiar with the system and its operation.

It's really difficult to say for certain, because there were some subtle differences between diesel engine configurations and the sequencing used to control them. If we understood the issues or concerns you had regarding the system we could provide a better "answer" to your post.

In general, the diesel engine had an engine-driven "hydraulic pump" and the pressure from that pump was routed through two or more solenoids to position the fuel rack of the diesel. The diesel has to be running for the fuel rack to be actuated by the solenoids.

Usually, one of the biggest problems associated with diesel engine starting means is that they don't automatically shut down. There is usually an electric solenoid that works by "turning" the armature of the solenoid (instead of the armature moving in/out like a plunger). That turning movement has to move the fuel rack mechanism to a position that reduces the fuel flow sufficiently to shut down the diesel (one can't just interrupt the spark plugs on a diesel!). Usually, this mechanism either gets old and "tired", or the holding bolts vibrate loose and the solenoid position needs to be readjusted, and a couple of drops of Loc-Tite will usually help stop the bolts from vibrating loose.

Usually, but not always, the diesel engine is "assisted" with breaking the turbine shaft away from rest (zero speed) by an assist from the Hydraulic Ratchet. So, when the diesel is accelerated away from its warm-up speed the Hydraulic Ratchet is started and the "bump" from the ratchet helps the diesel overcome the resting inertia of the turbine shaft to continue the turbine starting sequence. (When the diesel engine is started, there is usually a "warm-up" period before the diesel is accelerated to provide torque to the turbine shaft.)

Depending on the Starting Means configuration the Torque Converter may or may not have a solenoid to allow torque to be transmitted, or even to control the amount of torque being transmitted.

Many diesel engine starting means accelerate the diesel to one speed for purging and firing the turbine, and then once flame is established in the turbine the diesel is accelerated even further to provide an additional torque assist for accelerating the turbine shaft.

The details of your specific application should be found in the Instruction Manual originally provided with the unit. The Piping Schematic for the Starting Means system should provide the schematic representation of the system and depict the components the Speedtronic uses to control the starting/acceleration. The application code in the Speedtronic panel provides the specific details of how the system is controlled.

Sometimes, there is also helpful information in the Control Specification drawing, but that document has been overlooked in recent years and isn't much help for system descriptions any more (sad, but true).

So, if you have specific questions or problems or concerns, we could probably try to help here, but without access to the drawings and manuals and Speedtronic sequencing at your site, it's difficult to be specific about the system at your site.

If you have a Mark VI, I suggest you set up a Trend to record the parameters and I/O associated with a start. That can be very helpful in understanding and troubleshooting the starting sequence. The time to do this is *before* a problem arises, when everything is operating properly. That way, when a problem does occur the data can be compared to a good, typical start and analyzed to determine the cause of the problem.

If you are the original control.com markvguy, WELCOME BACK!
 
Thanks for your replay.

Actually i am going to work in old gas turbine plant (John Brown engineering) frame 5 built in 1974, and i just get only some paper from its P& ID.

i found its torque converter is (Twin disc) type old system, and Deisel engine is Detriot 500hp. If you explain them or if you have any document about this diesel engine and twin disc Torque converter please send it to me.

with my best appreciate
eng_abdalla
 
R

Radhakrishnan

TwinDisc torque converters used on these vintage machines don't require assistance from the ratchet mechanism.

I presume you have the old Mark II logic with you. Just compare that with the new Mark VI logic. since no changes are made on the unit, the logic associated with the diesel starter will basically be the same, whether you use Mark VI, Mark VIe or Mark xxx. If you are new to diesel starters, the information provided in the green books (turbine manuals) will help.

In essence, "no big deal".
 
I am looking for a Frame 5 torque converter. Is the one you are speaking about available?

I would also be interested in the Frame 5 unit as a whole.

Please reply here or email me direct at [email protected]
Thank you
 
I assume that this GT is already running and you try to understand the sequence.
MKII controlled FR5's with Diesel start motor usually had a one way solenoid valve which was controlling the governor speed of the Diesel engine. The older GT's were fired up between 20...25% speed (1200RPM).Post firing the GT will follow the warm up cycle for a minute and so till reaching FSNL.
If your upgrade from MKII to MKVI is done by OEM or a professional GT service company, the following modifications should have been done as a minimum:

HARDWARE:
Installing of the 3 way solenoid valve 20DAR1 and 20DAR2 with midpoint latching.

SOFTWARE (only control, DSM protection not described here):
Adding these new signals (L20DAR1 and L20DAR2 generic logical name). The design philosophy will be as following: Once the Diesel start motor (DSM) is started, it will warm up about 1min. after that your jaw clutch will engage via L20CS (if you have SSS clutch it will go automatically). One solenoid valve will accelerate (20DAR1) the speed the DSM and the other will decelerate (20DAR2).

Now comes the most important difference with the MKII and MKVI control: MKII fired the GT once the firing speed of about 20%. But MKVI will go about 20% but fire till the firing speed is within certain given parameters, lets say 2% or less. This setting is unit specific. MKVI will give pulse signals to the solenoids to match the speed which is set in the control constants.

Beside the mechanical governor problems, as CSA is indicating, the other problem you might experience is that, if this exact firing speed is not matched (usually because of pulse length setting in the MKVI) either you speed will not increase or overshoot above firing setting.

If somebody else will confirm the opposite, this will be a new invention and we will make business out of it.

Good Luck…Tempus Fugit…
 
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