Dissertation > Industrial Technology > Energy and Power Engineering > Steam Power Engineering > Steam boiler > Run > Combustion and adjustments

Mechanism and Experimental Study on Ignition and Low NO_x Emission Characteristics under High Concentration Pulverized Coal

Author SongGuoLiang
Tutor ZhouJunHu;ZuoKeFa
School Zhejiang University
Course Engineering Thermophysics
Keywords high concentration P.C ignition characteristics HCN NH3 release characteristics of NO_x pore structure characteristics optimal model
CLC TK227.1
Type PhD thesis
Year 2006
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The problem of high efficiency and low pollution during the pulverized coal (P.C.) combustion is one of the hot topics which many energy researchers are concerned about all the time. Though the technology of the high concentration pulverized coal combustion is of two characteristics of stable combustion and low NO_x emission, it is short of the theory guide of generalizing application in the engineering. Based on such engineering background, using the one-dimensional drop-tube furnace which is similar with the real P.C. furnace in thermal conditions, choosing the typical P.C. including anthracite and bituminous coal as well as lignite from the power plant, with the help of many analytical instruments, such as thermobalance, multi-component flue gas analyzer, scanning electron microscope (SEM), X-ray diffraction(XRD) and so on, combining the methods of macroscopic testes and microcosmic analysis, the detailed reaction mechanisms and the plentiful experiments were completed, the researches involve mainly the emission characteristics of carbon(C), hydrogen (H) and nitrogen (N) element and HCN, NH3 precursor as well as NO_x during the high concentration P.C. (0.248-2.136kgc/kga) combustion. Based on the abundant experiment data, the different factors affecting the ignition characteristics are analyzed thoroughly by the logic statistics, probability and grey system theory, and that the forecasting and optimal models under the high concentration are established. The main achievements in this dissertation are showed as follows:(1) Through the method of the thermo gravimetric analysis (TG) and the differential thermal analysis (DTA), the ignition and pyrolysis characteristics as well as dynamics parameters were researched under the stimulant high concentration P.C. When the concentration of P.C. was increased, both precipitation and burn-out temperature of volatile were reduced, the time of burnout was advanced, the maximal reaction velocity during the combustion was raised, and the ignition temperature and the active energy of P.C. were decreased. Moreover, each kind of coal had an optimal concentration, which was very favorable to the ignition.(2) The characteristics of temperature distribution of flue gas, dynamic change of furnace temperature and burnout for six typical kinds of coals were analyzed systematically under the different conditions, including the P.C. concentration, particles diameter, furnace temperature, wind temperature and oxygen quantity. The more the volatile of coals was, the bigger the increasing range of the flue gas temperature was, the optimal concentration of P.C. decreased. When coal particles

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