OCR Text |
Show To NOx generated out of a boiler, quite a number of different factors are overlapped and it is hard to define the influence of a single factor quantitatively. The factors can be listed as follows: (1) Fuel (2) Boiler structure (3) Combustion gas blow water (4) Combustion chamber thermal load (5) Combustion chamber sectional thermal load (6) Combustion chamber cooling surface thermal load (7) Burner structure and frame pattern (8) Number of burners and burner pitch (9) Refractory work at burner mounting section (10) Air ratio (11) Boiler operating load (12) Preheating temperature of combustion air (13) Others The above items are also important for the study of low NOx arrangement. NOx suppressing combustion technology for boiler The measure to reduce NOx discharge will be classified into the following three groups; (1) Reduction of Nitrogen content in fuel or conversion into the fuel or low Nitrogen content (2) Combustion conditions most hard for NOx to be generated (3) Removal of NOx in combustion discharged gas In this report, the above technology except (3) are dealt with as the theme, and the practical means for (1) and (2) are; (1) Use of good quality fuel(low organic nitrogen fuel) (2) Alteration of operating conditions(thermal control « technic) (a) Alteration of the range of operating air ratio (b) Reduction of combustion chamber thermal load (low output arrangement) (c) Reduction of air preheating temperature (3) Improvement of boiler proper and combustion equipments (a) Reduction of combustion chamber thermal load (Large sized combustion chamber) 9. - 9 - |