CO Emission during GTG DLN Tuning

[Instrumentworkhard]

Dear All.,

What I have found the problem so far during DLN tuning, our contractor require us to use secondary mornitoring..let's say CEMS.
How ever I offer them to take sampling at the exhaust by 3rd party lab mobile (400 to 50 decC) The result comparing with CEMS
(Actually CEMS already have compared with 3rd as well)is only CO. When they increase load every 30 min to base load the CO meaturing
velue at CEMS is too high and always over range multiply by 10 but the problem is CO at the exhaust is just only a bit.

They try to maintain NOx and O2 (normally NOx will be directed variation with Fuel and Heat) but CO shall be reversed. I beleive that
CO meaturing value for CEMS is correct but at the period loading rising CO was spouting to over range and contact to reading the value.
This point I found that the CO itself at mornitoring try to step down slowly and slowly then they change load again. For CO is quite fluctuated
when they step down I inform to contactor for holding load for 1 hour but they don't. Cause CO look like vary with NOx.

So I have assumed

1. Big different temperature between Stack and exhaust.
2. Insulation inside HRSG wood, fiber glass and so on (But it is 2 month comissioning)
3. Turbulence flow
4. Sampling take of point.
5. ????

 

[georgeverghese]

Not clear what the problem is; pls note that the reversible chemical reaction

CO + O2 = CO2 is favoured by low temps, so the CO level in the turbine exhaust ( where it is hotter), may be much lower than in your CEMS secondary monitoring (where the measurement is done at 50degC) - does this help ?