摘要
将煤与氨混燃逐步减少煤电是实现降碳的1种新途径,但煤氨混燃后的排放特性仍不清晰,需进一步从煤氨混燃方式与掺氨比对燃料排放特性的影响进行实验研究。因此,基于平焰燃烧器开展煤氨混燃实验,探究燃烧方式(预混、非预混)、掺氨比(0~100%)对排放特性的影响,采用烟气分析仪、热电偶与热重分析仪检测燃烧器上方高度沿程烟气中温度分布,并分析气体排放特性及飞灰特性。研究表明:当预混燃烧时,掺氨比越高,氨燃烧对煤氨气固燃料燃烧的促进作用越明显,即燃烧温度越高;而非预混燃烧时,掺氨比越高对燃烧越不利,即燃烧温度越低,但在燃烧前期消耗更多O_(2),是由于此时氨燃烧速率更快,且存在氨与煤争夺O_(2)的现象,体现了掺氨后对燃烧反应的抑制作用。在预混、非预混2种燃烧方式下,掺氨后相比于纯煤燃烧则NO_(x)大幅增加,纯氨燃烧时NO_(x)浓度均有降低的趋势,掺氨比增加,CO_(2)浓度降低,非预混燃烧时CO_(2)浓度低于预混燃烧。当掺氨比≥60%时,在剧烈反应段,根据质量变化速率曲线,质量变化速率峰由单峰逐渐向双峰转变,掺氨能够促进质量变化速率峰前移,说明掺氨燃烧后煤粉的孔隙结构发生改变;根据飞灰残碳率,当掺氨比<40%时更适合选择预混燃烧,当掺氨比>40%时则更适合选择非预混燃烧。总体来说,考虑煤氨气固燃料的排放特性,最佳的燃烧工况为预混燃烧方式、掺氨比为40%。
Reducing coal by co-combustion of coal and ammonia is a new way to achieve carbon reduction,but the emission characteristics after coal-ammonia co-combustion are still unclear,and further experimental research needs to be carried out for the influence of coal ammonia co-combustion method and ammonia mixing ratio on fuel emission characteristics.Therefore,the coal ammonia co-combustion experiments were carried out based on the flat flame burner,the influence of combustion mode(premixed,non-premixed)and ammonia mixing ratio(0~100%)on the emission characteristics was explored,and the flue gas analyzer,thermocouple and thermogravimetric analyzer were used to detect the temperature distribution in the flue gas along the height above the burner,and the gas emission characteristics and fly ash characteristics were analyzed.The results show that:when we do premix combustion,the higher the ammonia mixing ratio,the more obvious promotion effect of ammonia combustion,the higher the combustion temperature on the combustion of coal ammonia gas-solid fuel.When we do the non-premixed combustion,the higher the ammonia mixing ratio,the more unfavorable the combustion,the lower the combustion temperature.The consumption of more O_(2)in the early stage of combustion is due to the faster ammonia combustion rate at this time,and there is a phenomenon of ammonia and coal competing for O_(2),which reflects the inhibitory effect of ammonia doping on the combustion reaction.Under the two combustion modes of premixed and non-premixed,NO_(x)increases when the ammonia mixing ratio increases significantly compared with pure coal combustion after ammonia mixing,but the NO_(x)concentration decreases during pure ammonia combustion.When the ammonia ratio increases,the CO_(2)concentration decreases,CO_(2)concentration during non-premixed combustion was lower than that of premixed combustion.When the ammonia mixing ratio is≥60%,in the intense reaction stage,according to the weight loss rate curve,the weight loss rate peak gradually changes from single peak to bimodal peak,ammonia addition can promote the forward shift of the weight loss rate peak,which means that the pore structure of coal powder changes after combustion with ammonia.According to the residual carbon rate of fly ash,it is more suitable to choose premixed combustion when the ammonia mixing ratio is<40%,and non-premixed combustion when the ammonia mixing ratio is>40%.In general,considering the emission characteristics of coal ammonia gas-solid fuel,the best combustion condition is premixed combustion and ammonia mixing ratio is 40%.
作者
龚艳艳
GONG Yanyan(Beijing Tiandi Integration&Innovation TechnologyCorporation Ltd.,Beijing100013,China;National Energy Technology&Equipment Laboratory of Coal Utilization and Emission Control,Beijing100013,China)
出处
《煤质技术》
2023年第4期46-52,60,共8页
Coal Quality Technology
基金
北京天地融创科技股份有限公司科技发展基金重点资助项目(2023RCZD-05)。
关键词
煤氨混燃
排放特性
掺氨比
燃烧方式
气体组分
质量变化速率
孔隙结构
飞灰残碳率
coal ammonia mixed combustion
emission characteristics
ammonia ratio
combustion method
gas components
weight loss rate
pore structure
carbon residue rate of fly ash
