提出了助燃空气加湿式燃气锅炉低氮排放方式及热网利用余热与强化降氮2种不同运行模式。搭建了系统实验台,研究了液气比、助燃空气含湿量、运行模式对燃气锅炉降氮效果的影响。结果表明:提高助燃空气含湿量对降低燃气锅炉氮氧化物浓度...提出了助燃空气加湿式燃气锅炉低氮排放方式及热网利用余热与强化降氮2种不同运行模式。搭建了系统实验台,研究了液气比、助燃空气含湿量、运行模式对燃气锅炉降氮效果的影响。结果表明:提高助燃空气含湿量对降低燃气锅炉氮氧化物浓度效果显著;2种运行模式均可以大幅度降低氮氧化物排放浓度,甚至比燃气锅炉排放标准最新限值还低;相比热网利用余热运行模式,强化降氮运行模式的降氮效果更明显,可达到23.1 m g/m 3,可获得较高的低氮改造补贴;热网利用余热运行模式不仅可以使既有燃气锅炉达到氮氧化物排放标准,还具有较高的锅炉热效率,节能与环保的综合效益更好。展开更多
Context:Children with croup are often treated with humidity even though this is not scientifically based,consumes time,and can be harmful. Although humidity using the traditional blow-by technique is similar to room a...Context:Children with croup are often treated with humidity even though this is not scientifically based,consumes time,and can be harmful. Although humidity using the traditional blow-by technique is similar to room air and no water droplets reach the nasopharynx,particles sized for laryngeal deposition (5-10 μ m) could be beneficial. Objective:To determine whether a significant difference in the clinical Westley croup score exists in children with moderate to severe croup who were admitted to the emergency department and who received either 100% humidity or 40% humidity via nebulizer or blow-by humidity. Design and Setting:A randomized,single-blind,controlled trial conducted between 2001 and 2004 in a tertiary care pediatric emergency department. Participants:A convenience sample of 140 previously healthy children 3 months to 10 years of age with Westley croup score of more than 1 (scoring system range,0-17); 21 families refused participation. Intervention:Thirty minute administration of humidity using traditional blow-by technique (commonly used placebo,n = 48),controlled delivery of 40% humidity (optimally delivered placebo,n = 46),or 100% humidity (n = 46) with water particles of mass median diameter 6.21 μ m. Main Outcome Measure:A priori defined change in the Westley croup score from baseline to 30 and 60 minutes in the 3 groups. Results:Groups were comparable before treatment. At 30 minutes the difference in the improvement in the croup score between the blow-by and low-humidity groups was 0.03 (95% confidence interval [CI],-0.72 to 0.66),between low-and high-humidity groups,0.16 (95% CI,-0.86 to 0.53),and between blow-by and high-humidity groups,0.19 (95% CI,-0.87 to 0.49). Results were similar at 60 minutes. Differences between groups in pulse and respiratory rates and oxygen saturation changes were insignificant,as were proportions of excellent responders; proportions with croup score of 0 at study conclusion; and proportions receiving dexamethasone,epinephrine,or requiring additional medical care or hospitalization. Conclusions:One hundred percent humidity with particles specifically sized to deposit in the larynx failed to result in greater improvement than 40% humidity or humidity by blow-by technique. This study does not support the use of humidity for moderate croup for patients treated in the emergency department.展开更多
文摘提出了助燃空气加湿式燃气锅炉低氮排放方式及热网利用余热与强化降氮2种不同运行模式。搭建了系统实验台,研究了液气比、助燃空气含湿量、运行模式对燃气锅炉降氮效果的影响。结果表明:提高助燃空气含湿量对降低燃气锅炉氮氧化物浓度效果显著;2种运行模式均可以大幅度降低氮氧化物排放浓度,甚至比燃气锅炉排放标准最新限值还低;相比热网利用余热运行模式,强化降氮运行模式的降氮效果更明显,可达到23.1 m g/m 3,可获得较高的低氮改造补贴;热网利用余热运行模式不仅可以使既有燃气锅炉达到氮氧化物排放标准,还具有较高的锅炉热效率,节能与环保的综合效益更好。
文摘Context:Children with croup are often treated with humidity even though this is not scientifically based,consumes time,and can be harmful. Although humidity using the traditional blow-by technique is similar to room air and no water droplets reach the nasopharynx,particles sized for laryngeal deposition (5-10 μ m) could be beneficial. Objective:To determine whether a significant difference in the clinical Westley croup score exists in children with moderate to severe croup who were admitted to the emergency department and who received either 100% humidity or 40% humidity via nebulizer or blow-by humidity. Design and Setting:A randomized,single-blind,controlled trial conducted between 2001 and 2004 in a tertiary care pediatric emergency department. Participants:A convenience sample of 140 previously healthy children 3 months to 10 years of age with Westley croup score of more than 1 (scoring system range,0-17); 21 families refused participation. Intervention:Thirty minute administration of humidity using traditional blow-by technique (commonly used placebo,n = 48),controlled delivery of 40% humidity (optimally delivered placebo,n = 46),or 100% humidity (n = 46) with water particles of mass median diameter 6.21 μ m. Main Outcome Measure:A priori defined change in the Westley croup score from baseline to 30 and 60 minutes in the 3 groups. Results:Groups were comparable before treatment. At 30 minutes the difference in the improvement in the croup score between the blow-by and low-humidity groups was 0.03 (95% confidence interval [CI],-0.72 to 0.66),between low-and high-humidity groups,0.16 (95% CI,-0.86 to 0.53),and between blow-by and high-humidity groups,0.19 (95% CI,-0.87 to 0.49). Results were similar at 60 minutes. Differences between groups in pulse and respiratory rates and oxygen saturation changes were insignificant,as were proportions of excellent responders; proportions with croup score of 0 at study conclusion; and proportions receiving dexamethasone,epinephrine,or requiring additional medical care or hospitalization. Conclusions:One hundred percent humidity with particles specifically sized to deposit in the larynx failed to result in greater improvement than 40% humidity or humidity by blow-by technique. This study does not support the use of humidity for moderate croup for patients treated in the emergency department.
