干熄焦电站热力系统能量平衡分析

以能量平衡方程为依据,对唐钢炼焦制气厂干熄焦一车间电站热力系统进行热平衡和火用平衡计算,分析各环节的损失,确定余热锅炉耗能的薄弱环节,并提出进一步降低余热锅炉损失和提高余热锅炉效率的途径和改进措施,为干熄焦余热电站的深层次节能提供科学依据,也可为烧结等余热电站的优化设计提供借鉴。     

对干熄焦余热锅炉热力计算中传热系数的探讨

在锅炉的热力计算中,应对污染系数ε、热有效系数ψ和利用系数ζ等系数有准确理解。结合干熄焦余热锅炉实际烟气成分和运行实践,采用热有效系数沙ψ污染系数ε分别对各受热部件进行计算,通过对其参数的调整,反映出这些因素对传热系数的影响,提高热力计算的计算精度。同时,分析总结了特性参数调整的原因和规律,对同类余热锅炉的设计具有一定的指导意义。     

高压自然循环干熄焦余热锅炉应用前景分析

主要介绍国内外干熄焦余热锅炉的发展现状,随着能源短缺和不断增长的能源需求量,指出其向系列化、大型化、高参数发展应为必然趋势。分析对比了高压自然循环锅炉与中压混合循环锅炉的热力系统投资、运行费用、发电量和系统能源利用率,计算结果表明高压自然循环干熄焦余热锅炉具有较好的经济效益和工程应用前景。     

高压自然循环干熄焦余热锅炉热力特性研究

根据干熄焦的工艺特点,参考干熄焦余热锅炉运行经验,在保证自然循环安全可靠的基础上,设计研究干熄焦余热锅炉在高压下实现自然水循环的结构布置和热量分配情况,分析研究设计所得热力特性参数,为高压自然水循环干熄焦余热锅炉的进一步设计及研发提供了设计依据.     

LMTD法和ε-NTU法在余热锅炉传热计算中的对比应用及整体迭代优化

余热锅炉是燃气-蒸汽联合循环机组和多种化工工艺流程中的重要换热设备。余热锅炉属于典型的低温换热器,且蒸汽压力等级多,系统复杂,各模块间逻辑耦合性差,其热力计算与常规煤粉锅炉相比存在较多差异。以典型的自然循环余热锅炉为对象,对比研究了平均对数温差法(LMTD法)和有效度-传热单元数法(ε-NTU法)在余热锅炉传热计算中的应用,采用优选的算法建立了余热锅炉整体热力计算模型并对整体热力计算方法提出了优化。     

对煤矿热力系统节能问题的探讨

热能消耗占煤矿企业全部能源消耗的一半左右。提高煤矿企业的热能利用率是提高煤矿节能的一项重要的工作。通过提高锅炉的运行效率，对热力管网进行合理的布置，降低热力管网的散热损失，充分利用冷凝水的余热，达到降低能源总体消耗的目的。     

干熄焦余热锅炉烟尘特性分析及传热元件选型

干熄焦余热锅炉对干熄焦系统节能至关重要,如何保证余热锅炉安全高效运行,是干熄焦技术普遍应用的瓶颈之一。烟尘特性是影响干熄焦余热锅炉设计和运行的关键因素之一。通过在宝钢分公司炼铁厂三期干熄焦余热锅炉省煤器下部选取灰样,并对灰样进行工业分析、元素分析、灰分分析和粒度分析,并利用SEM观察其微观形貌,获得干熄焦余热锅炉的烟尘特性,进而提出干熄焦余热锅炉传热元件选型的建议,为干熄焦余热锅炉的设计和运行提供参考。     

供热汽轮机新汽耦合做功计算的研究

以常规热平衡法为基础,根据供热汽轮机凝汽循环和抽汽供热循环的实际耦合作用,推导出了考虑加热器散热损失的供热汽轮机热力系统等效热降与抽汽效率计算的矩阵方程,并将其应用于供热汽轮机新汽耦合做功的计算,其计算结果与常规热平衡法完全一致。本方法概念清楚,通用性好,为供热机组热力系统简捷快速地进行整体分析和局部定量计算奠定了基础。     

某电厂加装LPES低压省煤器的经济性分析

为了降低某电厂锅炉尾部烟道温度,减少排烟损失,提高锅炉效率从而达到节能的目的,通过在锅炉尾部烟道加装LPES低压省煤器,利用烟气余热加热凝结水这一措施来论证加装该设备后的经济性。实践结果表明,通过对低压省煤器系统建立数学模型、模型计算、实际测算并与其它电厂LPES低压省煤器相比较,得出加装低压省煤器对降低锅炉排烟温度,加热凝结水具有明显的效果。加装LPES低压省煤器后,锅炉排烟热损失下降明显,整个热力系统节能效果显著。     

600MW亚临界锅炉富氧改造热力学性能及?分析

利用锅炉热力计算和?分析的方法对某600 MW燃煤锅炉在不同O_2/CO_2气氛下进行锅炉热力特性和?效率计算,并与空气气氛下锅炉热力特性和?进行比较。结果显示:在富氧燃烧条件下,锅炉排烟量和排烟热损失有所减少,锅炉效率有所增加,同时锅炉的辐射和半辐射受热面的烟气侧换热系数增加。O_2/CO_2中氧气分压处于25%～30%之间时,锅炉的理论燃烧温度和炉膛出口温度与空气气氛相似。富氧条件下锅炉?效率提高1%左右,且?损失大部分发生在传热和燃烧过程中。     

常温空气无焰燃烧在燃煤锅炉煤改气中的应用

在燃煤锅炉的炉膛内安装常温空气无焰燃烧反应器,可将燃煤锅炉改造为燃气锅炉。计算表明与其它燃气锅炉以对流换热为主的热交换方式不同,该锅炉强化炉内换热,辐射换热量提高。实测结果锅炉热效率达到92.92%,比改造前提高30%以上,比现有同吨位的燃气锅炉高4%以上。由于锅炉实现了无焰燃烧,反应器温度分布均匀,尾气污染物排放远低于国家标准。     

Long-term thermal performance of a two-phase thermosyphon solar water heater

This article investigates experimentally the long-term thermal performance of a two-phase thermosyphon solar water heater and compares the results with the conventional systems. Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly, daily and long-term performance tests. Different heat transfer mechanisms, including natural convection, geyser boiling, nucleate boiling and film-wise condensation, are observed in the two-phase thermosyphon solar water heater while solar radiation varies. The thermal performance of the proposed system is compared with that of four conventional solar water heaters. Results show that the proposed system achieves system characteristic efficiency 18% higher than that of the conventional systems by reducing heat loss for the two-phase thermosyphon solar water heater.     

海拔高度对锅炉传热影响的理论分析

从现有的锅炉热力计算方法出发,分析推导了海拔高度的增加对锅炉炉内换热,对流放热系数,辐射放热系数和烟气物性的影响以及对锅炉总的换热量的影响,并指出了影响趋势。     

A conceptual design of solar boiler

State-of-the-art concepts for solar thermal power systems are based on parabolic trough, tower or parabolic disks either heating molten salts, mineral oil, air or generating steam. We propose in this paper, a conceptual design of a solar boiler. This concept comes from the conventional thermal power plants boiler, with the difference that the heat comes from mirrors that concentrate the solar radiation on wall-type array of solar collectors, instead of coming from fuel flames and hot gases. In our preliminary performance, analysis of this innovative solar boiler applied to electricity production, we have found that overall efficiency of the conversion from direct solar irradiation energy to electricity is above 20%, which is comparable to the value of parabolic trough and central tower technologies. Besides that, the concept seems very robust and could overcome some drawbacks derived from pressure losses, control complexity and material thermo-mechanical stress.     

Optimization of solar-powered Stirling heat engine with finite-time thermodynamics

A mathematical model for the overall thermal efficiency of the solar-powered high temperature differential dish-Stirling engine with finite-rate heat transfer, regenerative heat losses, conductive thermal bridging losses and finite regeneration processes time is developed. The model takes into consideration the effect of the absorber temperature and the concentrating ratio on the thermal efficiency; radiation and convection heat transfer between the absorber and the working fluid as well as convection heat transfer between the heat sink and the working fluid. The results show that the optimized absorber temperature and concentrating ratio are at about 1100 K and 1300, respectively. The thermal efficiency at optimized condition is about 34%, which is not far away from the corresponding Carnot efficiency at about 50%. Hence, the present analysis provides a new theoretical guidance for designing dish collectors and operating the Stirling heat engine system.     

Analysis of heat losses from a trapezoidal cavity used for Linear Fresnel Reflector system

A Computational study to investigate the heat loss due to radiation and steady laminar natural convection flow in a trapezoidal cavity having eight absorber tubes for a Linear Fresnel Reflector (LFR) solar thermal system with uniformly heated tubes and adiabatic top wall and side walls has been performed. The losses due to convection and radiation were considered from the bottom glass cover. The results are validated with experimental data. Radiative component of losses from the cavity was found to be dominant which contributes around 80–90%. Heat loss characteristics have been studied for cavities of different depths. Simulations have been carried out for various values of heat transfer coefficient based on the wind speed below the glass surface. Effect of emissivities of the tubes on the heat loss has also been simulated. Flow pattern and isotherms inside the cavity for various depths have been analyzed. Finally, the correlation between the total average Nusselt number and its influencing parameters has been obtained for the proposed cavity.     

整体煤气化湿化燃气轮机循环热力性能分析

本文以降低NOX排放和有效利用低品位热量为出发点,将燃料或空气湿化应用到整体煤气化燃气轮机循环中。基于水煤浆激冷或废锅流程气化炉,构建了多种整体煤气化湿化燃气轮机循环并分析了其热力性能。研究表明：燃料湿化循环系统效率较高;空气湿化循环燃气轮机比功较大;无论采用何种湿化方式,废锅流程循环系统效率都要高于激冷流程;蒸汽底循环保留的空气湿化循环系统具有利用系统外部中低品位热量、大幅提高系统效率的潜力。