CO WHEN COMBUSTION TURBINE LOAD CHANGES
CO WHEN COMBUSTION TURBINE LOAD CHANGES
(OP)
Can anybody explain in detail CO in relation to turbine loads on a 501 F or any gas turbine, natural gas unit. Is it because to much air flow vs gas flow or unburned fuel left behind. When a unit is producing higher Co on load changes or is it because IGV's are shifting with load going closed.
alocklear
Florida,USA
alocklear
Florida,USA
RE: CO WHEN COMBUSTION TURBINE LOAD CHANGES
So, if a GT is running near stoichiometric, and the load suddenly drops, the engine will accelerate. The increase in airflow will tend to drive the combustor mixture lean, decreasing CO (but possibly sending NOx levels up). The opposite case, a sudden increase in load, should cause the engine to momentarily decelerate, decreasing air flow, and drive combustors rich (driving up CO).
Modern engines (esp. fixed power generation turbines) run a "lean premix" combustion system, with preswirlers and other nifty technology. I wouldn't be surprised if, under some conditions, a reversal of the above "rule" could occur, due to aero effects of sudden changes in the complex burner flow path. (Fancy way of saying I could be wrong!)
- BT
RE: CO WHEN COMBUSTION TURBINE LOAD CHANGES
rmw
RE: CO WHEN COMBUSTION TURBINE LOAD CHANGES
The closure of the VIGV with decreasing load endeavours to maintain the equivalence ratio and thus combustion temperature by maintaining the turbine exhaust temperature (EGT). Although the combustion pressure decreases the higher combustion temperature helps reduce the increasing CO emissions at low loads. This is indeed the principle of DLE combustion where the equivalence ratio is now maintained at about 0.6 with load where the NOx and CO emissions are small.
We have developed some gas turbine simulators, which illustrate all these issues. If you wish, you can download them for evaluation. The website is www.gpal.co.uk.
Regards