COMPARISON ON EMISSION CHARACTERISTICS OF GASEOUS POLLUTANTS FOR THE CIVILCLEAN BRIQUETTE AND SCATTERED COAL OVER DIFFERENT HIGHLY EFFICIENT HEATING STOVES IN CHINA

摘要

Application of civil clean briquette equipped with highly efficient heating stoves is considered as one of the effective methods to reduce the air pollution of winter in rural areas of China.However,not much attention had been paid to the thermal efficiency and emission characteristics of gaseous Opollutants released from domestic heating stoves,in particular for considering the influence of the stoves power and fuel options.In current study,field measurements of the emission concentrations of the CO,CO2,NO,NO2,and particulate matter for civil clean briquette and scattered coal over the stoves with different powers were carried out,and the factors that affected that of the emission concentrations were also proposed.Based on the heating habits of the residents,three kinds of phases for ignition,flaming and smouldering could be classified to define the combustion progress.Results primarily showed that the thermal efficiency was improved by 0.24% - 0.28% /m2 on the fuel mass weighted basis due to the civil clean briquette substitution to the scattered coal over the stoves with 11 kW power.CO derived from the incomplete combustion and the improper mixing of air with volatiles of organic matter devolatilisation were significantly reduced,wheras the CO2 emission which is also an indicator of thermal efficiency was increased after implementing the substitution strategy.Occurrence of the lowest average CO/CO2 volume ratio was in flaming,thereby is the recommended phase.NOx emission was reduced by the decrease in fuel-nitrogen content for ignition and smouldering stages as well as by the reducing characteristic of the char in coal.Reduction in content of volatiles is the substantial reason that decreased the amount of particulate matter produced.In addition,stove with higher power is beneficial to the reduction in the concentrations of carbon oxides and particulate matter.The results can be employed as references for optimizing the operating conditions for burning the civil clean briquette.