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Show Ansaldo Energia s.p.a. \X- 0 fl D POFTO TOLLE #1 6C0MM rlg. 3 The boilers were oil/gas designed but operated only with oil so that reburning was implemented in oil over oil configuration. The final L o w - N O x performance of the system is given in the following figures 4 and 5 reporting, respectively, Low-NOx performance in different operating modes (fig. 4) and, for an optimized condition, N O x response over the load range (fig. 5). f«< Ku»imroiun w w . UHBBnuurnutmi* \~ 54N:w X x X * • IL •« WIT2 -M W M 1 (ITS <rra B T Z 1 + 1,2% 0,45% Organic Nitrogen S T Z < 0,25% 0,35% Organic Nitrogen minimum N O x obtained by air staging averaged 250 mg/Nm3 3 % 0 2 Reburn fuel quality provided larger operational margins (the S T Z oil is the reference oil burnt by E N E L to assure contemporary control of N O x and SOx limits without using FGD's) Reburn operation proved to be the key element for combined NOx/CO/particulate matter control in the high load range (100-H70% M C R ) , being the "pure air staging" operating mode sufficient to provide compliance with the law limits at lower boiler loads. r,t M W l f M TMIrl/ • ttww. 8 i - x 8 "» I m 1 ( • * - • • • , "^ • - • -j Mi .«o« •20 -10 • NO. OFA . N O FEB O CO OFA 4 CO BE B • OuaCFA • Qua FEB Results gathered in unit 1 retrofit and intensive C F D modeling indicated that the post combustion air injection system could be improved by adding a forth O F A on each boiler side wall. This improvement has been applied in unit 4 obtaining the results presented in fig. 6 To be noted that N O x , C O and particulate levels reported in figure 6 are plotted against the stoichiometry at reburn elevation. a m *^^ 4 MO 4 • J A • • NO. OFA iNOiQIREB • CO OFA .COOJREB IT*" ' ^ • •»»• M• i.£- *•<.'^" **7 "- ™ * • < «• • *- - . - A • DuaOFA • OuaQlREB Figures 4 and 5 allow to draw some interesting conclusions : • Reburn proved largely superior to simple air staging infact even in the 250 m g C O range the A T Z 2 4- 2,2% S 0,52 Organic Nitrogen |