MINIMIZATION OF NO EMISSIONS FROM MULTI-BURNER COAL-FIRED BOILERS

Eddings, E.G. ; Molina, A. ; Pershing, D.W. ; Sarofim, A.F. ; Davis, K.A. ; Fletcher, T.H. ; Zhang, H.

National Energy Technology Laboratory (U.S.)

关键词: Boilers;    Nitric Oxide;    Chars;    01 Coal, Lignite, And Peat;    Mathematical Models;   

DOI  :  10.2172/786861
RP-ID  :  FG26-97FT97275--06
RP-ID  :  FG26-97FT97275
RP-ID  :  786861

美国|英语

来源: UNT Digital Library

【 摘 要 】

During the last reporting period the experimental setup in the University of Utah Laminar-Flow Drop Tube was modified to allow for batch experiments. This modification was made in order to guarantee complete conversion of the char in the reactor. Once the setup was optimized, the effect of particle size, oxygen concentration, type of char and NO bulk concentration on the conversion of char-N to NO was evaluated. In this report, we present the results obtained for different chars and for different NO background concentrations. The effect of oxygen and particle size is currently being analyzed and will be presented in the final report. Experiments were performed with three different carbonaceous materials and were conducted at temperatures close to that of pulverized combustion conditions (1700 K) in a laminar drop tube reactor under inert and oxidizing atmospheres. The results obtained show that the process of NO reduction on the char surface plays an important role on the total amount of char-N converted to NOx. This effect tends to reduce as the NO background concentration is reduced and doesn't seem to strongly depend on the nature of the char. Some of these results were presented at the 2nd Joint Meeting of the US Sections of the Combustion Institute, held in March of 2001. In addition to the experimental observations on char-N conversion to NO, a single particle model was developed and the predictions of the model were compared with the experimental results. Although the model predicts the linear reduction on the conversion of char-N to NO, it overpredicts the general value. A higher value for the rate of NO destruction on char surface doesn't seem to explain this phenomenon, which may be more related to the availability of char surface for the destruction of NO.