CAJ | 학술논문

选用大颗粒木质燃料为研究对象，通过管式加热炉对单颗粒木质燃料进行燃烧试验，研究不同空气流量和温度下木质燃料燃烧过程CO、NO、SO2等气体动态排放特性。试验结果表明：800℃时，挥发分着火时间滞后，着火前即有CO 随挥发分析出，CO 排放浓度曲线呈双峰状；随着温度升高，CO 析出峰明显变窄，从挥发分析出至焦炭燃烧完成所需时间缩短；NO排放浓度及其排放量在温度为900℃时达到最大值，燃料N至NO的转化率最高可达41.79%，随着温度升高和燃烧过程还原性气氛增强，NO 析出浓度及其排放量减少，转化率可低至12.32%；木质燃料充分燃烧时，几乎无SO2排出，S主要转化为硫酸盐固存于灰分中或于高温下随烟气排出；贫氧燃烧状态下，SO2析出主要源自挥发分析出初期有机硫的分解、氧化，但燃料中更多的S以H2S、CaS等形式排出。
선용대과립목질연료위연구대상，통과관식가열로대단과립목질연료진행연소시험，연구불동공기류량화온도하목질연료연소과정CO、NO、SO2등기체동태배방특성。시험결과표명：800℃시，휘발분착화시간체후，착화전즉유CO 수휘발분석출，CO 배방농도곡선정쌍봉상；수착온도승고，CO 석출봉명현변착，종휘발분석출지초탄연소완성소수시간축단；NO배방농도급기배방량재온도위900℃시체도최대치，연료N지NO적전화솔최고가체41.79%，수착온도승고화연소과정환원성기분증강，NO 석출농도급기배방량감소，전화솔가저지12.32%；목질연료충분연소시，궤호무SO2배출，S주요전화위류산염고존우회분중혹우고온하수연기배출；빈양연소상태하，SO2석출주요원자휘발분석출초기유궤류적분해、양화，단연료중경다적S이H2S、CaS등형식배출。
Due to the influence of the mass and heat transfer, some obvious differences in flue gas emissions may occur during the combustion of wood powders and pellet. However, many studies report on the characteristics of flue gas emissions during wood powder combustion, and researches on the single wood pellet combustion and its flue gas emission are limited. The aim of this work was to obtain dynamic data on the release of CO, NO, and SO2 during single large wood pellet combustion by performing experiments in a tube furnace under different temperatures (800, 900, 1 000, 1 100, and 1 200℃) and air flow rates (3, 4, and 5 L/min). The results from the experiment can serve as an important reference for efficient and clean combustion of biomass. The total emissions and their conversions from biomass combustion can be quantified with these data. The experimental results showed that CO emission curve present a double-peak shape at 800℃, mainly because of its slow devolatilization and combustion in low temperature. With increasing temperature, CO emission time decreased, indicating that it needed shorter time during devolatilization and char burnout. Because of sufficient burning, the peak CO concentrations and total CO emissions almost decreased as the temperature grown in 4, 5 L/min air flow rate. NO was released to the gas phase in significant amounts at 900℃, while decreased with increasing temperature or reducing air flow rate. A part of NO was transformed to N2 with the reductive gas of CO as the temperature increased. At temperatures of 1 100 and 1 200℃, NO forming through HCN and NH3 declined because of inadequate oxygen supply in 3 L/min air flow rate. The change tendencies of NO emissions in 4 L/min air flow rate were similar to the change tendencies in 5 L/min air flow rate, probably associated with CO emissions in 4, 5 L/min air flow rate. Fuel-N conversion rate reached the minimum and maximum values (12.32%, 41.79%) in 3 L/min air flow rate under the combustion temperature of 1 200℃ and 5 L/min air flow rate under the combustion temperature of 900℃,respectively. During wood pellet sufficient burning, no SO2 was released to the gas phase, since sulfur mainly converted to sulfate stored in ashes or discharged with the flue gas at high temperature. Above 1 100℃, SO2 emission was observed presumably by organic sulfur oxidation or sulfate dissociation in 3 L/min air flow rate, mainly because of the low conversion of SO2 transformed to sulfates under the condition of lean oxygen. Calculations indicated that 33.78% and 25.99% of the fuel-S was released to the gas phase as SO2 at 1 100 and 1 200℃,respectively. On the contrary, most sulfur in the wood pellet discharged with the forms of H2S, CaS, etc.