I want to know how the compressor stall detection algorithm for heavy duty gas turbines in MARK VI works? and how the configured stall parameters contribute in detecting the compressor stall? and what would be the initial compressor discharge pressure?

 

HMR,

Unfortunately, if I recall correctly axial compressor stall detection is accomplished in firmware (i.e., at the VME card level) and so the algorithm is not generally visible in Toolbox. I think some newer versions of Toolbox and Mark VI may have an "algorithm" in application code, but some of them are actually macros (for lack of a better term) and troubleshooting or understanding them can be difficult if not impossible.

If the Mark VI uses an algorithm in application code, have you tried right-clicking on the "block" and selecting "Block Help"? If so, did you not find the information helpful (if available)?

Axial compressor stall generally occurs when one stage of the compressor is not able to push the air to the next stage, resulting in a stoppage (stall) of the air flow. It's pretty sudden, and is usually accompanied by a large "bang" noise. I believe the axial compressor discharge pressure also drops precipitously, which is basically what the stall detection algorithm is looking for.

Stall detection, though present in most Mark Vs, Mark VIs, and Mark VIes, isn't usually enabled for anything other than GE-design heavy duty F-class units (and I would imagine the LMS--100 units) or aero-derivative units.

I have seen many non F-class units have erroneous and nuisance stall detection alarms during start-up and shutdown that were easily solved by disabling the stall detection because it should never have been enabled to begin with. It's necessary for F-class units because the axial compressors are usually operating very near compressor operating limits to achieve rated power output and so if ambient conditions or machine conditions (compressor cleanliness; compressor clearances; low-frequency operation; etc) are such that the compressor is truly operating at or near its limits then the condition may be true--and dangerous.

What unit are you presently working on/with, and what issues are you having with stall detection?

When is stall detection being annunciated? During starting/loading? During shutdown? During loaded operation?

If during loaded operation, can you describe the operating conditions when you are having problems?

Does the unit have conventional or DLN combustors?

I <b>DO NOT</b> want to imply or suggest the issue isn't real, but you haven't provided enough information to be of much help, and unless the algorithm has a 'Block Help' description then I can't be of too much more help without a LOT more information.

 

Dear CSA

Thanks a lot for the detailed answer. i have recently been relocated. previously i was working on 3 Gas Turbines (GE 10-1) and now i have been assigned to work on 2 (MS-5001) gas turbines, & yes both turbines have a DLN combustors but there are no issues with the compressor and no alarm is generated due to compressor stall. but i came across this algorithm & yes you are right the algorithm executes in the firmware. but i was unable to understand how this algorithm works. I can email you the document, if you can go through it, it is a very brief document which explains how this algorithm works, we are not facing any problems i am just curious how it works, hope you can understand this