OCR Text |
Show A165E713.T 6 As one would expect, Figure 1 shows increased NOx emissions with increasing load for each of the turbines tested, with the exception of those equipped with NOx control. Peak load NOx emissions for the turbines ranged from 27 to 200 ppmc, which is indicative of the varying fuel/air ratios and heat release rates associated with each of the gas turbine models. Low load NOx emissions (25 % MCR) ranged from 19 to 54 ppmc due to reduced thermal NOx production as ambient temperature effects NOx emissions of gas turbines. NOx emissions for the Solar Mars T14000 SoLoNOx and GE Frame 7 gas turbine do not follow the trend exhibited by the other turbines due to their NOx control design. The design of the SoLoNOx dry 10w-NOx combustor maintains reduced peak flame temperature through operation of the combustor in a premixed mode. Maximum NOx emissions of 40 ppmc were seen at 50 % load, with minimum NOx emissions of 24 ppmc at 75 % load. The GE Frame 7 controlled NOx emissions via increased rates of water injection at higher loads. The range of ambient conditions to which a given turbine will be exposed must also be taken into consideration in evaluating compliance monitoring strategies. CO emissions are presented in Figure 2 in units of ppm at 15 % O2 (ppmc). Each of the turbines tested during this program exhibited lower CO emissions with increasing load. A comparison of Figures 1 and 2 shows that turbines with higher NOx emissions (Le., higher combustor and exhaust temperatures) produced lower CO emissions. Since CO is a product of incomplete or low temperature combustion, factors that reduce CO emissions (e.g. increased fuel/air mixing) frequently lead to higher temperatures and thus higher NOx emissions. Maximum CO emissions of 2,209 ppmc were measured at 35 % load on the Solar Mars T14000 SoLoNOx gas turbine, with minimum CO emissions of 1.9 ppmc measured at peak load on the General Electric Frame 3 gas turbine. CO emissions from the General Electric Frame 3 gas turbine were essentially constant for the three load points (50 %, 75 % and 100 %) tested. AIR TOXIC EMISSIONS RESULTS Metals Emissions (Utility Combustion Turbines) The results of the metals tests on the two utility turbines are presented in Table 6. The fIfteen metals tested fall into three discreet groups on each unit: those detected at more than twice the fIeld blank levels, those detected at less than twice or below the fIeld blank levels, and these that were not detected. Barium, chromium, copper, and nickel were detected at more than twice the fIeld blank level on both turbines, while manganese was detected only on the Westinghouse turbine and lead was detected only on the GE turbine. The measured levels were all low compared to emissions from coal- and oil-fued boilers. The possible sources of the trace metals are the fuel, the combustion air, or sample contamination. Ambient air samples conducted at both units indicate that ambient air is not a likely source of trace metals in the exhaust gas. Fuel analyses conducted as part to the program were not sensitive enough to determine if the fuel could be the source of the metals seen in the samples. Turbine surfaces are a possible source of chromium and nickel, since both are present |