Accurate carbon emissions data of gas units is one of the guarantees to ensure carbon trading. Many gas units recently installed online gas chromatography devices

so that the carbon emission is able to be real-time monitored from fuel part. For units that are not equipped with flue gas CO2 monitoring system or have no enough equipment space

conversion with flue gas O2 concentration is one of the feasible paths to monitor carbon emission from flue gas part. But whether direct measurement or conversion monitoring methods

there is still a lack of sufficient research on the deviation of continuous monitoring data from the fuel part and flue gas part. Therefore

for the gas units without capability to directly monitor flue gas CO2 in the short term

this study takes the historical data of an F-class gas-steam combined cycle unit for the simulation

and conducts continuous simulation monitoring and analysis based on the conversion with flue gas O2 concentration and online gas chromatography. It is found that there is no stable sorting rule of the monthly data and the relative deviation between different calculation methods.All the relative deviation of annual data is less than 5%. The correlation between δRD

R

fluegas-flue-h and the O2concentration of CEMS is the highest. The deviation of carbon emission amount in the unit is mainly in the stable combustion section with a load ratio of more than 55%. In accordance with current standards or specifications

the O2 concentration of CEMS and the wet flue gas flow rate at the chimney outlet is most likely to cause the deviation of carbon emission amount from the fuel part and flue gas part. Under the existing technical specifications

the carbon emission from fuel part and flue gas part can be monitored in real time

which can be used for analysis on trend

but only the uncertainty of result from fuel part is below 5%. For gas units

the carbon emission monitored at fuel part is more appropriate

and the method monitoring the flue gas part may be more suitable for coal-fired units.