| OCR Text |
Show level, but did not meet the CO target level of 100 ppmv. When combustion air was increased to meet the 100 ppmv CO limit, NOz reduction across the catalyst did not occur and the NOz 9 target level was not achieved. p~ ~(J~ As long as the catalyst effluent remained at slightly u~-__ r reducing conditions, the catalyst enhanced the reaction ~ between NOz and the excess fuel beyond the kinetic capabili- ~ ties of thermal reduction. To investigate this discovery, the catalyst was divided into two sections. The process was modified to include the following steps: 1A. of fuel to NOz from the Thermal reduction with a slight excess remove all oxygen and about 50% of the incoming flue gas. dUV\) --~ °Fz... I, I ())( 2A. 3A. 4A. 5. 6. Cooling of the products from step 1A. J-/~:CV;;- I Mixing of products with less than stoichiometric _ ,r'f).(\J f~ combustion air. '" II!>' v r v Catalytic reduction of the remaining NOz to less than 25 ppmv. @~ 7)1)-/J\rO~ Co Mixing of products with an excess of combustion air. Catalytic oxidation of excess combustibles to less than 100 ppmv CO (dry basis). In an effort to provide two catalyst stages--one reducing and one oxidizing--the single catalyst bed consisting of three cylindrical monoliths was divided into two sections. The reduction section contained two-thirds of the original catalyst bed, with the oxidation section consisting of the remaining one-third. However, dividing the original catalyst bed into two sections did not provide sufficient catalyst in either section for conclusive results. The test program was therefore restructured to enable adequate demonstration of the process with the properly specified and sized catalyst beds. PROBLEM SOLUTION Radian decided to modify the test equipment to incorporate the correct type and amount of catalyst in the two beds. The supplier of the oxidation catalyst for the initial demonstration testing was contacted to evaluate the Hybrid Low NOz Cogeneration Process and recommend a reduction catalyst for step 3A of the revised process. A platinum-rhodium catalyst that was developed to reduce NOz in the exhaust of rich-burn stationary engines was recommended. -3- |
