OCR Text |
Show were studied [5]. The results of this work suggested a number of methods for substantial NOx reduction, particularly by optimisation of the mixing between the fuel and air streams [4-6]. The results of NG6 also suggested further areas for research and optimisation and led to a second series of experiments being initiated by the NGNOX Consortium. The objectives of this programme was to further evaluate the NOx reduction techniques studied in NG6 and to investigate further novel NOx reduction srategies. This experimental programme is known as NG7 and was executed in November 1990, [1]. Figure 4. Natural gas fired glass tank simulator In the NG7 experiments, the experimental set up was essentially identical to NG6 (see Figure 4). The main input conditions were: • fuel input: 0.5 MW • fuel: natural gas · • combustion air: 11000C • combustion air velocity: 10 mls • excess air ratio: 1.1 • . gas firing modes: underport, overport, throughport, sideport and parallel sideport .• gas injection ·modes: ·central, annular and swirled The experiments coI1centrated on optimisation of the mixing process between the fuel jet and the combustion air. In Figure 5, the different gas · injection methods, investigated during the NG7 programme,are shown. Methods of |