Investigation Of The Measurement Of OH-PLIF In Pulverized Coal Combustion

Coal is the most important primary energy in the world and plays a very important role in China's energy structure.It is the great significance to study coal combustion mechanism and develops clean and efficient coal burning technology for energy conservation and emission reduction.The complex structure and composition of coal cause that the combustion reaction includes multiphase physicochemical reaction process,which brings great difficulties to the mechanism research.PLIF technology has the advantages of high temporal resolution,high spatial resolution and high sensitivity,etc.,and has obtained many important achievements in the study of the combustion characteristics of pulverized coal.OH-PLIF reflects the information of flame structure and temperature by detecting the fluorescence signal of hydroxy(OH)after excited transition by using ICMOS camera.At present,the main research directions are divided into low-frequency(<10 Hz)PLIF to study the macroscopic characteristics of pulverized coal group combustion,and high-frequency(~10 kHz)PLIF to study the ignition characteristics of single particle pulverized coal.The frequency utilization interval is large,and there are no scholars have studied the combustion behavior of single particle coal in group coal powder.Therefore,this thesis will use multiple PLIF technologies to study the combustion characteristics of pulverized coal,so as to evaluate the application range of PLIF technology in studying the combustion characteristics of pulverized coal and other solid particles.At the same time,the macroscopic characteristics of pulverized coal group combustion and the microscopic characteristics of single particle were measured.In this thesis,10 Hz PLIF was used to obtain the influence law of coal particle group combustion characteristics of five factors including coal particle class,coal particle size,environmental temperature,environmental oxygen concentration and particle feeding rate.The results show that the ambient temperature has little effect on the characteristics of pulverized coal,and all other factors have certain influence on the ignition delay and OH signal strength of particle group combustion.Using 500 Hz PLIF technology,the continuous volatiles combustion process of single particle in coal powder group was obtained,and the change information of flame shape,OH signal intensity and motion velocity in the volatiles combustion process were obtained.The combustion characteristics of pulverized coal particles are analyzed by comparing the results of statistical analysis with the results of 500 Hz PLIF.At last,PLIF technology of 5 kHz and 10 kHz is used to study the ignition process of single particle in coal-burning powder group,and its ignition mode is analyzed.Combined with OH-PLIF results of coal-burning powder group,the influence of different ignition modes on subsequent combustion characteristics is compared and analyzed.Different PLIF measurement methods are suitable for studying different aspects of pulverized coal combustion characteristics.By selecting appropriate PLIF parameters,the macroscopic combustion characteristics,microscopic change process and early ignition and combustion mechanism of pulverized coal particle swarm can be studied,which has great advantages and development potential in the research of solid particle combustion characteristics.