In order to determine the sensitivity of influencing factors on NOx emission in gas-fired heating and hot water combi-boilers,the orthogonal method was adopted in this paper.Five predominant factors affecting the form...In order to determine the sensitivity of influencing factors on NOx emission in gas-fired heating and hot water combi-boilers,the orthogonal method was adopted in this paper.Five predominant factors affecting the formation of NOx and four levels were selected to be analyzed,including the diameter of flue restrictor,power of fan,ejection distance of nozzle,aperture of nozzle and relative humidity of air.The test plan was designed by employing L16(45)orthogonal array,and 16 groups of experiments were conducted.The test results were analyzed with range analysis and variance analysis.The results indicated that the power of fan has the greatest influence on the formation of NOx of the gas-fired combi-boilers,followed by the diameter of flue restrictor and the relative humidity of air,while the ejection distance of nozzle and aperture of nozzle have little effect on the formation of NOx.In addition,with the selected optimal combination of five factors,a minimum NOx volume fraction is obtained,which confirms the superiority of the orthogonal test.The research finding has a certain guiding significance for the reduction of NOx formation of gas-fired heating and hot water combi-boiler.展开更多
Hazard control of NOx is very important for the long life of hot stove shell and environmental protection. NOx concentrations during different operation periods of hot stove were calculated according to thermodynamica...Hazard control of NOx is very important for the long life of hot stove shell and environmental protection. NOx concentrations during different operation periods of hot stove were calculated according to thermodynamical and dynamical analyses. The results were verified by the previously measured data. Then, the influence of hot stove oper- ation parameters on NOx concentration and the mechanism of liquid water formation in hot stove were studied. The results indicated that in gas period, the dome temperature should be controlled below 1420 ℃ in order to decrease NO~ emission. In the case of banking operation, NOx concentration was about 40--60 times higher than that in gas period. Hence, reasonable measures should be taken to reduce banking operation, especially in the situation of large excess air ratio. Since NOx formed during the whole operation process, the most effective way of preventing liquid water and HNO3 generation is to control the pipe and shell temperature, which should be higher than the condensa- tion temperature of water vapour. The condensation temperature should be considered as the design temperature of pipe and shell for hot stove.展开更多
INTRODUCTION I built my first“green”structure when I was ten years old-a multilevel tree house with views of my backyard and the woods beyond.The whole thing was built from lumber cast off(with permission,honestly)f...INTRODUCTION I built my first“green”structure when I was ten years old-a multilevel tree house with views of my backyard and the woods beyond.The whole thing was built from lumber cast off(with permission,honestly)from a construction site down the road and hauled in by kids with wagons.Old nails straightened with hammers,a rusty handsaw for the cuts and a rickety ladder borrowed from some kid’s father got us that fort in the sky-and my first experience in recycling and reuse.Actually,I had the privilege of growing up around talented people with solid skills.My grandfather worked on the Old Ironsides renovations at the shipyard in Boston.My father taught me his renovation skills.I worked on a house build when I was fourteen with a man who was a natural at creating beautifully engineered trusses and carriers.When I was a twenty-year-old UConn student,I spent my weekends in New Hampshire helping friends build their summer home out of salvaged materials.Did the experience stick?Who knows?But this dyed-in-the-wool Yankee has always considered material reuse and recycling to be an important part of any build or renovation project.展开更多
基金funded by the Key Project in the Tianjin Science and Technology Pillar Program under grant number 19YFZCCG00550。
文摘In order to determine the sensitivity of influencing factors on NOx emission in gas-fired heating and hot water combi-boilers,the orthogonal method was adopted in this paper.Five predominant factors affecting the formation of NOx and four levels were selected to be analyzed,including the diameter of flue restrictor,power of fan,ejection distance of nozzle,aperture of nozzle and relative humidity of air.The test plan was designed by employing L16(45)orthogonal array,and 16 groups of experiments were conducted.The test results were analyzed with range analysis and variance analysis.The results indicated that the power of fan has the greatest influence on the formation of NOx of the gas-fired combi-boilers,followed by the diameter of flue restrictor and the relative humidity of air,while the ejection distance of nozzle and aperture of nozzle have little effect on the formation of NOx.In addition,with the selected optimal combination of five factors,a minimum NOx volume fraction is obtained,which confirms the superiority of the orthogonal test.The research finding has a certain guiding significance for the reduction of NOx formation of gas-fired heating and hot water combi-boiler.
基金Sponsored by National Natural Science Foundation of China(61271303)
文摘Hazard control of NOx is very important for the long life of hot stove shell and environmental protection. NOx concentrations during different operation periods of hot stove were calculated according to thermodynamical and dynamical analyses. The results were verified by the previously measured data. Then, the influence of hot stove oper- ation parameters on NOx concentration and the mechanism of liquid water formation in hot stove were studied. The results indicated that in gas period, the dome temperature should be controlled below 1420 ℃ in order to decrease NO~ emission. In the case of banking operation, NOx concentration was about 40--60 times higher than that in gas period. Hence, reasonable measures should be taken to reduce banking operation, especially in the situation of large excess air ratio. Since NOx formed during the whole operation process, the most effective way of preventing liquid water and HNO3 generation is to control the pipe and shell temperature, which should be higher than the condensa- tion temperature of water vapour. The condensation temperature should be considered as the design temperature of pipe and shell for hot stove.
文摘INTRODUCTION I built my first“green”structure when I was ten years old-a multilevel tree house with views of my backyard and the woods beyond.The whole thing was built from lumber cast off(with permission,honestly)from a construction site down the road and hauled in by kids with wagons.Old nails straightened with hammers,a rusty handsaw for the cuts and a rickety ladder borrowed from some kid’s father got us that fort in the sky-and my first experience in recycling and reuse.Actually,I had the privilege of growing up around talented people with solid skills.My grandfather worked on the Old Ironsides renovations at the shipyard in Boston.My father taught me his renovation skills.I worked on a house build when I was fourteen with a man who was a natural at creating beautifully engineered trusses and carriers.When I was a twenty-year-old UConn student,I spent my weekends in New Hampshire helping friends build their summer home out of salvaged materials.Did the experience stick?Who knows?But this dyed-in-the-wool Yankee has always considered material reuse and recycling to be an important part of any build or renovation project.
