This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of ...This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The infuence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.展开更多
The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a neg...The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a negative emission method to capture CO2 produced by carbon contained in biomass.In the past decades,many studies have been carried out regarding experiments and numerical simulations under oxy-fuel combustion conditions.This paper firstly briefly discusses the techno-economic viability of the biomass and coal co-firing with oxycombustion and then presents a review of recent advancements involving experimental research and computational fluid dynamics(CFD)simulations in this field.Experimental studies on mechanism research,such as thermogravimetric analysis and tube furnace experiments,and fluidized bed experiments based on oxy-fuel fluidized beds with different sizes as well as the main findings,are summarized as a part of this review.It has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxyfuel fluidized beds.We summarize a recent survey of published CFD research on oxy-fuel fluidized bed combustion,which categorized into Eulerian and Lagrangian methods.Finally,we discuss the challenges and interests for future research.展开更多
在碳达峰、碳中和背景下,发展燃煤与生物质耦合发电是加快电力转型升级、实现煤电低碳发展的重要途径之一。在某台300 MW循环流化床(CFB)锅炉上设计建设了一套燃煤直燃耦合生物质的燃烧发电系统,并利用该系统进行了燃煤直燃耦合生物质...在碳达峰、碳中和背景下,发展燃煤与生物质耦合发电是加快电力转型升级、实现煤电低碳发展的重要途径之一。在某台300 MW循环流化床(CFB)锅炉上设计建设了一套燃煤直燃耦合生物质的燃烧发电系统,并利用该系统进行了燃煤直燃耦合生物质的燃烧特性试验研究。结果表明:该生物质直燃耦合系统运行稳定可靠;CFB锅炉在掺烧木屑颗粒燃料时,随着掺烧比的增加,混合燃料的飞灰含碳量下降、CO排放量降低,混合燃料的燃尽性得以改善;掺烧后经过锅炉燃烧配风优化,锅炉NOx排放量比纯烧原煤排放量略有降低。试验典型工况污染物测试表明:掺入木屑颗粒燃料后,锅炉烟气二噁英排放量为0.0088 ng TEQ/m^(3)(标准工况,φ(O_(2))=11%,下同),飞灰中二噁英排放量为0.0206 ng TEQ/m^(3);飞灰中重金属及P、As、Se等有害微量元素排放值总量为32.121mg/L;底渣中重金属及P、As、Se等有害微量元素排放值总量为3.918 mg/L,烟气和飞灰中的二噁英和重金属等有害物质排放均满足国家环保标准排放限值。展开更多
【目的】研究Rothermel林火蔓延速率预测模型及另外2种以Rothermel模型为核心的蔓延速率预测模型对南方8种典型森林地表死可燃物的适用性,为林火蔓延速率预测提供理论支撑和指导。【方法】以南方地区8种典型速率地表死可燃物为对象,根...【目的】研究Rothermel林火蔓延速率预测模型及另外2种以Rothermel模型为核心的蔓延速率预测模型对南方8种典型森林地表死可燃物的适用性,为林火蔓延速率预测提供理论支撑和指导。【方法】以南方地区8种典型速率地表死可燃物为对象,根据研究对象的野外实际条件,在东北林业大学帽儿山实验林场风洞实验室内,构建不同可燃物床层含水率、载量及高度的可燃物床层,每种可燃物在平地无风条件下进行36次点烧试验,共288次点烧,记录每种可燃物类型不同配比条件下的蔓延速率。通过直接使用Rothermel模型、重新估计Rothermel模型参数、对Rothermel模型形式改进后自建模型的对比,得到最合适的预测模型。【结果】 1)平地无风条件下,南方8种典型森林地表死可燃物床层最大蔓延速率为0.55 m ·min -1 ,平均蔓延速率由大到小依次为:华山松、云南松、毛竹、柳杉、杉木、马尾松、麻栎及青冈栎。2)直接使用Rothermel模型预测的林火蔓延速率误差较大,平均绝对误差为0.18 m ·min -1 ,平均相对误差为70.0%。3)重新估计参数后的Rothermel模型及自建模型,预测的可燃物蔓延速率精度显著提高,平均绝对误差分别为0.04、0.037 m ·min -1 ,平均相对误差分别<18%、16.45%。4)重新估计参数的Rothermel模型与自建模型的预测误差的差异不显著,其中自建模型的预测值与实测值的 R 2 变化在0.71~0.90,平均为0.80。【结论】对南方8种典型森林的地表死可燃物类型,在平地无风条件下,重新估计参数的Rothermel模型及自建模型的预测精度相近,但自建模型可能更简单易用,可预测平地无风条件下可燃物地表火蔓延速率。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 90210034, 50576101,20221603)
文摘This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The infuence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.
基金supported by the Key Program of the National Natural Science Foundation of China(51736002)the Natural Science Foundation of Jiangsu Province(BK20180386).
文摘The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a negative emission method to capture CO2 produced by carbon contained in biomass.In the past decades,many studies have been carried out regarding experiments and numerical simulations under oxy-fuel combustion conditions.This paper firstly briefly discusses the techno-economic viability of the biomass and coal co-firing with oxycombustion and then presents a review of recent advancements involving experimental research and computational fluid dynamics(CFD)simulations in this field.Experimental studies on mechanism research,such as thermogravimetric analysis and tube furnace experiments,and fluidized bed experiments based on oxy-fuel fluidized beds with different sizes as well as the main findings,are summarized as a part of this review.It has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxyfuel fluidized beds.We summarize a recent survey of published CFD research on oxy-fuel fluidized bed combustion,which categorized into Eulerian and Lagrangian methods.Finally,we discuss the challenges and interests for future research.
文摘在碳达峰、碳中和背景下,发展燃煤与生物质耦合发电是加快电力转型升级、实现煤电低碳发展的重要途径之一。在某台300 MW循环流化床(CFB)锅炉上设计建设了一套燃煤直燃耦合生物质的燃烧发电系统,并利用该系统进行了燃煤直燃耦合生物质的燃烧特性试验研究。结果表明:该生物质直燃耦合系统运行稳定可靠;CFB锅炉在掺烧木屑颗粒燃料时,随着掺烧比的增加,混合燃料的飞灰含碳量下降、CO排放量降低,混合燃料的燃尽性得以改善;掺烧后经过锅炉燃烧配风优化,锅炉NOx排放量比纯烧原煤排放量略有降低。试验典型工况污染物测试表明:掺入木屑颗粒燃料后,锅炉烟气二噁英排放量为0.0088 ng TEQ/m^(3)(标准工况,φ(O_(2))=11%,下同),飞灰中二噁英排放量为0.0206 ng TEQ/m^(3);飞灰中重金属及P、As、Se等有害微量元素排放值总量为32.121mg/L;底渣中重金属及P、As、Se等有害微量元素排放值总量为3.918 mg/L,烟气和飞灰中的二噁英和重金属等有害物质排放均满足国家环保标准排放限值。
文摘【目的】研究Rothermel林火蔓延速率预测模型及另外2种以Rothermel模型为核心的蔓延速率预测模型对南方8种典型森林地表死可燃物的适用性,为林火蔓延速率预测提供理论支撑和指导。【方法】以南方地区8种典型速率地表死可燃物为对象,根据研究对象的野外实际条件,在东北林业大学帽儿山实验林场风洞实验室内,构建不同可燃物床层含水率、载量及高度的可燃物床层,每种可燃物在平地无风条件下进行36次点烧试验,共288次点烧,记录每种可燃物类型不同配比条件下的蔓延速率。通过直接使用Rothermel模型、重新估计Rothermel模型参数、对Rothermel模型形式改进后自建模型的对比,得到最合适的预测模型。【结果】 1)平地无风条件下,南方8种典型森林地表死可燃物床层最大蔓延速率为0.55 m ·min -1 ,平均蔓延速率由大到小依次为:华山松、云南松、毛竹、柳杉、杉木、马尾松、麻栎及青冈栎。2)直接使用Rothermel模型预测的林火蔓延速率误差较大,平均绝对误差为0.18 m ·min -1 ,平均相对误差为70.0%。3)重新估计参数后的Rothermel模型及自建模型,预测的可燃物蔓延速率精度显著提高,平均绝对误差分别为0.04、0.037 m ·min -1 ,平均相对误差分别<18%、16.45%。4)重新估计参数的Rothermel模型与自建模型的预测误差的差异不显著,其中自建模型的预测值与实测值的 R 2 变化在0.71~0.90,平均为0.80。【结论】对南方8种典型森林的地表死可燃物类型,在平地无风条件下,重新估计参数的Rothermel模型及自建模型的预测精度相近,但自建模型可能更简单易用,可预测平地无风条件下可燃物地表火蔓延速率。
