please throw some light on this. When we give a start command to a gas turbine (say GE make, 19.6 MW, Frame-5, Mark-VIe control with prime mover is diesel engine), what are the steps through which it reaches FSNL (full speed no load). i.e., Functional description of starting of gas turbine. I just want to know details step-wise. Our machine is very old (1984), but upgraded gradually & most of old manuals are not available. I hope this is the best forum to learn this type of query.
If you haven't already used the cleverly hidden 'Search' feature of control.com, I heartily recommend you do so. I believe this topic (start-up process of GE-design heavy duty gas turbine) has been covered MANY times before on control.com.
Also, you would need to tell us what fuel(s) the unit can be started on (for example, some units primarily burn naphtha, but they can be started or stopped on naptha and must be started or stopped on distillate (diesel; HSD (High Speed Diesel); LSD (Low-Sulfur Diesel) or possibly natural gas. Or they burn propane and must be started and stopped on natural gas or distillate fuel. Some machines are dual fuel capable--usually natural gas and distillate. Some machines can burn distillate and heavy fuel oil. So, we need to know what fuel(s) the turbine can be started on at your site.
Also, a diesel engine starting means is not a prime mover. The turbine is a prime mover for the generator. Generators have prime movers; turbines do not. Generator prime movers can be hydro turbines, reciprocating engines (which might burn gasoline, diesel, natural gas, methane, etc.), steam turbines, etc. A gas turbine must have a starting means--a means of breaking the turbine (and generator) shaft(s) away from zero speed and purging the turbine of combustible gases before the ignition source is energized and fuel is admitted to establish flame. And, during and after the firing (if successful) the starting means is still required to help the unit accelerate because there is insufficient torque being developed by the turbine to keep it spinning and to accelerate to what is termed "self-sustaining" speed where the torque developed by the turbine is sufficient to continue the acceleration to rated speed (also called FSNL, Full Speed-No Load). The starting means usually includes some type of torque-producing machine (a diesel engine; an electric motor; a steam turbine; an expander turbine (similar to a steam turbine but uses some other medium (such as compressed natural gas) to develop torque to apply to the turbine-generator shaft) and a torque converter.
The torque converter is required because the starting means cannot be directly coupled (bolted to) the turbine shaft and develop torque. Most starting means have to spin up to their operating speed to develop sufficient torque to help break the turbine shaft away from zero speed and purge the turbine and exhaust and provide the torque required for acceleration to self-sustaining speed. The torque converter is the method (machine) that lets the starting means and turbine-generator shafts spin at different speeds so that the starting means can provide maximum torque while the turbine-generator shaft accelerates and purges and accelerates to self-sustaining speed.
So, we need more information from you and you should do some searching on control.com. The 'Search' feature is cleverly hidden at the far right of the Menu bar of every desktop webpage of control.com. (If you're using the Mobile version of control.com, 'Search' is found under the 'Control.com' tab.) You should probably use the 'Search' Help the first few times you use 'Search' because the syntax of the search terms is NOT like your preferred World Wide Web search engine. But, control.com's 'Search' is fast and powerful--once you learn how to use it!
It's really a shame that the original Operations & Service Manuals cannot be found.... While the turbine and control system may have been upgraded, the essentials probably haven't changed all that much. It's pretty likely the System Descriptions are still as applicable today as they were when the unit was new and would be valuable to you as you are just starting out.
Looking forward to hearing back from you! (If you haven't guessed by now, I like original posters to provide information so that I don't have to guess very much or provide too much information that may or may not be applicable. I also firmly believe that people should be involved in learning--because they retain much more than if they are just "handed" information.)