| Along with the progress of human society and the development of the process of industrialization, energy from coal and oil polluted environment. Pollution is becoming more and more serious and has become a common concern of social issues. As a kind of high efficiency and less pollution energy, natural gas is going to replace coal and oil gradually and provide clean energy for human society. Gas turbine in a mechanical equipment to convert natural gas to electricity, will play an important role to the development of human society.Gas turbine has problems of flame instability and high NOx emission in the combustion, are some of the main reasons to restrict development of domestic heavy gas turbine. This paper comprehensive summarized the current development of gas turbine domestic and foreign. Research on base of GT13E2 gas turbine which imported from Switzerland Alstom, studied the characteristics of EV burner and annular combustion chamber. Focused on the study of optimization switching conditions of gas turbine, NOx emission characteristics of pilot flame and mix flame, impact of the fuel gas proportion change between main premix and small premix to characteristics of flame stability and NOx emission.The main research progress in the paper are as follows:(1) The combustion chamber is easy to flame off because of low frequency pulsation during gas turbine load switch over point. Experimental study to find optimized load switch over condition. Experimental results show that, gas turbine load switch over point at 58% relative base load, No. 43 gas control valve close activate delay time at 0.2S, combustion chamber pulsation fluctuation is small and pulsation peak value is low during load switch over. Flame is stable and combustion chamber is not easy flame off.(2) The combustion chamber is also easy to flame off because of low frequency pulsation during gas turbine load switch back point. The load switch back process is more complicated than load switch over process and have more influence factor. Experimental study to find optimized load switch over condition. Experimental results show that, gas turbine load switch back at 57.5% relative base load, No.41 control gas valve close delay time at 0.5s after switch back point command activate, No.42 control gas valve open delay time is 0.3s after switch back point command activate, No.43 control gas valve takes 1s to supply gas flow from 0 kg/s to rated flow after switch back point, combustion chamber pulsation fluctuation is small and pulsation peak value is low during load switch over. Flame is stable and combustion chamber is not easy flame off.(3) Pilot flame research results show that NOx generated under pilot flame mainly belongs to the thermal NOx. Thermal NOx caused by flame heterogeneity and rich flame, part flame temperature exceed 1500℃. NOx emission exceed 60 ppm at gas turbine idle mode and increase along with gas turbine load. NOx emission exceed 80 ppm at 26% relative base load. NOx emission reduced effectively after premix flame put into operation.(4) The premixed flame research results show that premixed flame is lean burn and NOx emission is low. The natural gas/air equivalence ratio of small premixed flame is lower than main premix flame, small premix flame can modify the combustion chamber temperature field and reduce NOx emission. When gas turbine operate with mix flame, increase the natural gas proportion of premix flame can reduce the pilot flame natural gas, thereby reduce rich flame to reduce NOx emission. Experimental results show that natural gas proportion of main premix flame increase with gas turbine load, NOx emission keeps at 70 ppm. While natural gas proportion of small premix flame increase with gas turbine load, NOx emission appears downward trend and can be reduced to nearly 30 ppm.(5) Gas turbine operate with premix flame in high relative load. Pure main premix flame experimental results show that NOx emission exceed 95 ppm when gas turbine operate above 65% relative base load, NOx emission reach 120 ppm when gas turbine operate with base load. Auxiliary premix flame experiments selected gas turbine operate with 65%, 70%, 80%, 90% relative rated load and rated load to reduce NOx emission by adjusting natural gas proportion of small premix flame. The experimental results show that gas turbine operate with 65%, 70%, 80%, 90% relative rated load and rated load, NOx emission are lower than 22 ppm when natural gas proportion of small premix flame keep at 18%, 20%, 22%, 22% and 22% correspondingly to meet the natural gas power plant NOx emission requirements, also low frequency pulsation of combustion chamber fluctuate small and flame are stable. |
PDF Full Text Request