共查询到19条相似文献,搜索用时 187 毫秒
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天然气锅炉尾部增设冷凝换热装置,可以回收烟气中的显热及潜热,是锅炉节能的重要技术措施.对于大量中小型微正压燃烧的天然气锅炉,在实施这项技术中,存在的技术瓶颈是节能装置增加的阻力必需在燃烧器风机的压头裕量之内.由于微正压燃烧器的风机压头裕量通常较小,如果增设节能装置的阻力超过其裕量,则会影响原燃气锅炉的正常运行,出现炉门冒烟、出力不足等故障.介绍一台成功运行的微正压燃气锅炉所增设的节能装置中一组错列翅片管束和一组顺列翅片管束在低雷诺数下运行的阻力特性试验研究情况及相应的试验关联式,可供设计运行单位参考. 相似文献
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在风洞实验台上,对椭圆矩形翅片管束和圆管圆形翅片管束进行了对比性实验,归纳出了换热与阻力的无因次经验公式,对于管内蒸汽冷凝、管外空气横掠管束的工况,椭圆矩形翅片管具有较优的换热与阻力性能。最后,讨论了一些有关椭圆矩形翅片管冷凝器的优化问题 相似文献
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自然通风直接空冷系统凝汽器单元"Λ"型布局和传统翅片结构使得冷却空气流过翅片管束时发生严重转向,从而显著影响空冷凝汽器的流动传热性能。提出了一种新型翅片管束,其翅片通道与基管椭圆长轴方向呈一定夹角,使翅片通道方向与塔浮升力方向平行。通过CFD数值模拟和实验验证,获得了采用新型倾斜翅片管束的自然通风空冷凝汽器的空气流场和温度场,计算得到了不同环境风速下空冷凝汽器总换热量的变化规律,并与现有翅片管束的空冷凝汽器性能进行了对比。研究结果表明,采用倾斜翅片空冷凝汽器可以显著改善自然通风直接空冷系统热力性能,降低机组背压,提高空冷机组运行的经济性。 相似文献
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富氢燃气将成为双碳时代低碳或零碳社会发展的重要着力点,其燃料掺混与冷凝增效的综合节能降碳潜力可达10%~30%。以燃气冷凝换热系统构建为突破口,通过数据分析发现传统冷凝换热拟合关联式误差来源,通过实验研究揭示富氢燃气锅炉燃烧后烟气中水蒸气冷凝换热过程中蒸发冷凝多因素耦合转移交互作用机制,首次提出多参数冷凝换热装置显热与潜热强化换热数学关联式,并在此基础上提出冷凝换热装置的微元迭代数字设计优化方法,首次实现冷凝换热器数字化精确设计,直接支撑双碳时代富氢燃气锅炉余热冷凝回收节能降碳10%左右的目标。 相似文献
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高水分烟气对流冷凝换热模拟实验研究 总被引:9,自引:2,他引:9
针对冷凝式燃气锅炉,利用加湿热空气模拟燃气锅炉尾部烟气,通过实验研究了不凝性气体占多数时的水蒸气冷凝换热,研究了不同水蒸气分压比(3%—20%)、不同温度下(100—200℃),加湿空气的冷凝换热特性。实验表明,不凝性气体(空气)占多数时,其对流冷凝复合换热系数可以达到无冷凝时干空气对流换热系数的1.5-3倍。复合换热系数的影响因素主要有水蒸汽分压力Pv、Pe、Pr以及壁面温度Tw和混合气体主流温度Tg,在此基础上建立一个新的准则数Ln并拟合了冷凝换热Nu数的准则关系系。 相似文献
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介绍了各种类型的管外冷凝强化换热管,分析了其强化机理及结构特点,并总结得出:管外冷凝强化管的换热系数与管型有关,且各管型的结构参数对强化传热具有重要的作用.对国内外管外冷凝强化技术研究工作进行分析,结果表明,目前管外冷凝强化换热管的研究主要集中于翅片形状、翅片密度、翅片高度等结构参数对换热性能的影响.强化换热管的冷凝传热性能不仅与翅片结构参数有关,而且也与管材的表面特性和导热系数有关.管外冷凝强化换热管的研究重点是开发新型三维结构翅片的双侧强化管并研究其传热关联式,以及研究不锈钢等低成本材料制造的强化管换热管的传热性能和强化结构的优化. 相似文献
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在回收燃气锅炉烟气余热时,采用特殊管型强化传热以吸收烟气中大量的水蒸气所携带的显热和潜热,可以降低锅炉的排烟温度,提高锅炉的热效率。对滴型管和圆管烟气侧传热特性进行数值计算,通过对计算结果的分析比较,探讨了影响传热的因素,得出滴型管的传热特性优于圆管的结论,为特殊管型在冷凝换热器中的应用提供参考。 相似文献
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在分离式冷凝锅炉的换热装置系统中处理烟气中,处理冷凝水的方法通常是通过净化处理再利用。本文的分离式冷凝锅炉冷凝水处理方案是将冷凝水经系统处理作为锅炉的给水,将冷凝换热装置节约的能量直接反馈回锅炉,由于锅炉负荷的波动带来烟气温度与给水流量的变化,导致冷凝率不稳定,所以本文中采用理论方法计算冷凝水量。 相似文献
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A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE) and cyclone separator were calculated according to the relative operation data at different boiler loads. Moreover, the heat transfer coefficient of the waterwall was calculated by heat balance of the hot circuit of the CFB boiler. With the boiler capacity increasing, the heat transfer coefficients of these heating surface increases, and the heat transfer coefficient of the water wall is higher than that of the platen heating surface. The heat transfer coefficient of the EHE is the highest in high boiler load, the heat transfer coefficient of the cyclone separator is the lowest. Because the fired coal is different from the design coal in No.1 boiler, the ash content of the fired coal is much lower than that of the design coal. The heat transfer coefficients which calculated with the operation data are lower than the previous design value and that is the reason why the bed temperature is rather high during the boiler operation in No.1 boiler. 相似文献
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Evaluation of retrofitting a conventional natural gas fired boiler into a condensing boiler 总被引:3,自引:0,他引:3
The exit flue gas temperature of a conventional gas fired boiler is usually high and a great amount of heat energy is lost to the environment. If both sensible heat and latent heat can be recovered by adding a condensing heat exchanger, the efficiency of the boiler can be increased by as much as 10%. In this paper, based on combustion and heat transfer calculations, the recoverable heat and the efficiency improvement potential of different heat recovery schemes at various exit flue gas temperatures are presented by performing design calculations. The payback period method has been used to analyze the feasibility of retrofitting a conventional gas fired boiler into a condensing boiler in a heating system in detail. The results show that the most economical exit flue gas temperature is 40–55 °C when a conventional natural gas fired boiler is retrofitted into a condensing boiler simply by adding a condensing heat exchanger. It is feasible to use the return water of a heating system as the cooling medium of the condensing heat exchanger because the return temperature varies with the ambient temperature and is lower than the dew point of the water vapor in the flue gas in most periods of a heating season in some regions, which has been verified by retrofitted case. 相似文献
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An experimental system investigating condensation heat transfer of wet flue gas was set up, and the heat transfer performance of vapor‐gas mixture with vapor condensation was discussed. The experimental results of laminar flow in a plastic longitudinal spiral plate heat exchanger were obtained and are in good agreement with the modified classical film model. It is shown that the plastic air preheater can avoid acid corrosion in the low‐temperature field for the boiler using fuel containing sulfur and recover latent heat of the water vapor of the wet flue gas. Also some SO2 was scrubbed during the vapor condensing process in the heat exchanger. © 2001 Scripta Technica, Heat Trans Asian Res, 30(7): 571–580, 2001 相似文献