NOx reduction at cogeneration plant with incineration plant by injecting ammonia

In the autumn of 1999 the IC plant at Nordborg Power Plant was commissioned, and following that the emissions and emission reductions of the plant were measured. The measured CO and UHC values are considerably below the emission limits specified in Order no.720 of October 1998 issued by the Ministry of Environment and Energy. During Low-NOx operation, the NOx emission level is also below the limits. Since the quantity of NOx is not reduced in the IC plant but only by changing the motor adjustment, it was pointed out as early as at the commissioning of the plant that injection of ammonia in the plant would in all probability produce a NO_x reduction. This report discusses this possibility. Having realised the tests, the following overall conclusions have been reached: 1) It has been established that it is possible to reduce the NOx emission from the plant by injection of ammonia. 2) It has been demonstrated in a test rig that large quantities of ammonia will give a reduction of about 50%. 3) Injection of ammonia in the flue gas before the plant has been found to be without effect. 4) Model analyses have demonstrated that injection of ammonia directly into the combustion chamber of the IC plant will give a NOx reduction of about 45%. Conclusively it can be said that it is technically possible to reduce NOx emissions by injection of ammonia, but it is not an economic advantage compared to changing the motor adjustment to Low-NOx operation. This conclusion stands so long as the present economic and technical conditions remain the same