分离式冷凝型天然气锅炉的研究与应用

介绍了常用冷凝型锅炉结构,重点讨论了分离式冷凝锅炉的特点,实验研究了以空气和水为冷却介质的烟气冷凝换热的规律,常规锅炉与烟气冷凝热能回收装置构成的冷凝锅炉系统的工程应用获得了满意的结果,节能与环保效益显著。     

具有混合气体冷凝的燃气锅炉系统

介绍了常用的冷凝型锅炉结构,重点讨论分离式冷凝锅炉的特点。天然气锅炉烟气中含有相当比列水蒸汽,携带大量汽化潜热,与燃煤锅炉明显不同,提供了更大的余热利用空间。针对燃天然气热水锅炉,研制开发了采用烟气冷凝热能回收装置的锅炉系统并应用于实际。运行测试表明,改造的锅炉运行正常,提高锅炉热效率5%以上,节约大量天然气,同时吸收烟气中部分NOx,起到一定净化作用。本系统投资回收期短,节能与环保效益显著。     

小型燃气冷凝式锅炉的开发

冷凝式燃气锅炉是节能和环保型锅炉,通过增加尾部受热面对烟气进行冷凝换热,吸收烟气中水蒸气的汽化潜热,降低排烟温度。对冷凝式锅炉烟气冷凝方案不同的换热设备进行相应的分析讨论,并采用搪瓷省煤器对烟气进行冷凝换热,锅炉的热效率明显提高。     

湿烟气冷凝换热的数值模拟

为了对湿烟气冷凝换热过程进行深入细致的研究,采用计算流体动力学(CFD)方法对某湿烟气冷凝换热装置进行数值模拟,得到了该装置内部的速度场、压力场、温度场和传热系数的分布情况,并将其应用到某330 MW亚临界燃煤机组上.结果表明:本文数值模拟结果与该湿烟气冷凝换热装置实际运行结果基本吻合,可以作为同类装置的重要设计依据.     

基于多台冷凝式锅炉的给水系统的优化设计

针对多台冷凝式锅炉组成的系统,为提高燃气锅炉余热回收率,提高锅炉热效率,设计了一套给水系统。在一台或多台锅炉运行时给水系统实现自动分配,充分保证在用锅炉冷凝式节能器的进水量,使烟气中的水蒸气有效冷凝,达到高效节能的目的。优化结果表明,排烟温度降到烟气露点以下,锅炉热效率均可达102%以上,单台锅炉提高效率7%以上。冷凝式节能器进水量达到最大进水量的1/3时,调节进水阀开度,锅炉排烟温度随着进水流量的增大而减小,锅炉效率随着进水流量的增加明显提高。     

冷凝式锅炉排烟热损失计算方法探讨

冷凝式锅炉回收了排烟中的显热和水蒸气的凝结潜热,锅炉效率可达105%以上。由于其节能环保的特点,近年来冷凝锅炉在国内得到了快速发展。目前GB/T 10180-2003《工业锅炉热工性能试验规程》以及相关资料中的排烟热损失均只在无冷凝水析出的情况下适用,对于烟气中有冷凝的情况无法进行计算,本文对天然气冷凝锅炉排烟热损失计算方法进行了初步探讨。     

燃气锅炉烟气冷凝水回收利用的设计计算及探讨

集中供热锅炉安装烟气余热回收装置是国家推行提高锅炉效率的重要途径,以咸阳某热力公司91 MW燃气热水锅炉安装烟气余热回收装置为例,分析了其稳定运行工况下冷凝水产生量以及冷凝水化学成分,采用一定方式处理后进行再利用,其节能、节水效果显著。     

富氢燃气锅炉冷凝换热系统及装置的双碳重构设计和优化

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。     

避免锅炉尾部受热面低温腐蚀的方法与锅炉结构的研究

文中论述了锅炉尾部低温腐蚀形成的原因以及危害,提出一种使用“水-风”换热系统来进行防腐的方法,该系统包括空气预热器与烟气冷却器,空气预热器将锅炉给水中的热量传给助燃空气,烟气通过五级烟气冷却器后温度降至高于烟气露点的135.6℃,避免了烟气中的SO2与水蒸汽形成H2SO3,从而解决锅炉尾部低温腐蚀的问题,该系统经热平衡...     

突破露点,回收烟道气体热量的新技术

锅炉出口烟气将锅炉燃料中约13％的热量传给了呔气,这是一项为数可观的损失。回收烟气余热的措施很多,但采用一般传统方法均不能突破露点的制约。本文所介绍的方法技术新颖、一反常规,具有相当重要的价值。将烟气中所含水蒸汽降温冷凝,可回收大量热能,用以加热锅炉给水,预热空气和提供生产和生活用热水。目前已有500多套采用这种新技术的机组在欧洲使用,节能效果十分显著。     

Evaluation of retrofitting a conventional natural gas fired boiler into a condensing boiler

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.     

天然气锅炉改造为冷凝式锅炉的经济性评价

燃气供热锅炉排烟温度较高，带走了大量的热能。如果加装冷凝式换热器回收烟气的显热及潜热，可以大大提高锅炉效率，但是加装换热器必然增加设备成本。本文通过对冷凝式换热器设计计算，计算出不同排烟温度下的热能回收设备投资回收期，从经济上分析了天然气锅炉改造为冷凝式锅炉的可行性，并给出了锅炉最佳排烟温度。     

吸收式热泵在燃气采暖冷凝热回收中的应用

作者建立了一种利用吸收式热泵回收燃气锅炉冷凝热的系统，解决了供热回水温度高而难以回收烟气冷凝热问题，比现有的锅炉烟气冷凝热回收技术提高效率5％以上。计算分析结果表明，这一工艺的应用可产生显著的经济、节能和环保效益。     

燃气锅炉烟气在滴型管外传热特性的数值分析

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。     

脱硫后烟气冷凝酸液质量分数的数值预测

通过检测烟囱内冷凝酸液质量分数可以预测其腐蚀程度,但获取具有代表性的冷凝酸液样本十分困难．为解决这一难题,采用修正逸度方程与Matlab软件对1台300Mw安装湿法烟气脱硫装置的烟气冷凝酸液质量分数进行了数值预测,分析了烟气中水蒸气体积分数、壁面温度和烟气绝对压力对烟气冷凝酸液质量分数的影响．结果表明：冷凝酸液质量分数随着壁面温度的升高而增大,随着烟气绝对压力的提高而减小,随着烟气中水蒸气体积分数的增大而减小;预测值与试验值相吻合,该预测模型可以很好地模拟对冷凝酸液质量分数的预测．     

660 MW超超临界锅炉净烟气取水装置的优化研究

为适应内蒙古地区干旱缺水的环境特点,降低火电机组的水耗,针对660 MW超超临界褐煤锅炉的技术特性,提出并应用了一套回收锅炉烟气中水分并加以利用的节水装置.该装置通过在脱硫塔出口烟道内加装冷却器,降低了烟气温度,使得烟气中的水蒸气受冷凝结,并汇集成有利用价值的液态水.实际运行结果表明,该烟气取水装置具有节水效果显著、出...     

Theoretical prediction of sulfuric acid condensation rates in boiler flue gas

Prediction of acid condensation has a critical role in designing heat exchangers to recover water vapor from power plant flue gas. Rates of mass transfer for condensation of sulfuric acid vapors onto heat exchanger tubes were theoretically investigated and a computer program for numerical simulations of sulfuric acid (H₂SO₄) condensation in a flue gas condensing heat exchanger was developed. Governing equations based on mass and energy balances for the system were derived to predict variables such as flue gas exit temperatures, cooling water outlet temperatures, and molar fractions and condensation rates of water and sulfuric acid vapors. The associated equations were solved using an iterative solution technique and a one dimensional finite difference method with forward differencing. The Controlled Condensation Method (EPA Method 8B) was applied to experimentally obtain concentration profiles of sulfuric acid vapor in flue gas along downstream in the system. Predicted results of sulfuric acid vapor condensation were compared with empirical data for model validation, and the discrepancy is analyzed in terms of measurement and computation uncertainties. It is found that from both modeling and test results sulfuric acids as well as water vapors are reduced and separated in condensing heat exchanger due to mass transfer with condensation in flue gas. The modeling methodology described here is applicable to theoretical prediction of sulfuric acid and water condensation in full scale flue gas condensing heat exchanger applications.     

An experimental study on vapor condensation of wet flue gas in a plastic heat exchanger

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