浅谈蒸汽供热调节

本文主要介绍蒸汽在工作状态下参数的计算方法和热网中蒸汽运行的调节手段。     

供热工程中的蒸汽喷射式热泵

介绍蒸汽喷射式热泵基本原理,优点,使用场合,节能计算和技经分析等。     

蒸汽供热系统对流水击研究

汽水管路、贮水容器或蒸蒸汽锅简等蒸汽供热设备经常发生水与蒸汽的对流冲击,是影响锅炉及用汽设备运行的常见故障之一。本文分析产生对流水击的热力学原因,导出对流水击速度与强度的计算方法,并结合实例给出计算结果。     

供热汽轮机抽汽供热循环做功计算的研究

以常规热平衡法为基础,通过严格的数学推导,首次将等效热降理论应用于供热汽轮机抽汽供热循环做功与做功不足的计算,并得出了相应的计算模型.实例计算表明,本模型通用性好,计算准确简捷,为供热汽轮机热电联产总热耗量合理分配的研究奠定了基础.     

蒸汽供热系统工质回收率

凝水回收率做为蒸汽供热系统的节能评价指标之一.已为人们所熟知和重视.然而,凝水回收是否真实反映供热系统的质量回收情况?在节能评价时有没有比它更方便更科学的评价指标来代替?这一指标是否比凝水回收率具有更好的可测得性和可分析性?本文从蒸汽供热的系统角度提出系统工质回收率的概念并依热平衡原理建立工质回收率关系式,使其具有明显的可测得性和便于分析的特性.     

电厂蒸汽长距离供热分析

随着经济的快速发展,供热市场潜力巨大,且多以稳定的生产工艺热负荷为主.但电厂与热用户之间的距离相对较远,国家现行的供热相关标准已经不能满足工业快速发展的现状,所以迫切需要解决长距离供热问题.通过数值计算得到管道内部蒸汽流动时压力和温度随长度的变化关系,然后利用计算机编程计算出机组在不同抽汽参数和输送管径下的供热距离并进...     

蒸汽引射器引射汽轮机排汽供热的研究与应用

为了缓解电厂出现的供热不足问题和减少冷端损失,提出了通过蒸汽引射器引射汽轮机乏汽用于供热的方法,并对蒸汽引射器引射汽轮机排汽的工作原理进行了分析介绍。以某330 MW的机组为例,对其利用蒸汽引射器引射汽轮机排汽进行了热力和经济性分析。结果表明:增设蒸汽引射器后,在一个供暖周期内可以为电厂增加供热量367.62 GJ/h,有很大的节能潜力。     

化工装置利用热泵回收废热蒸汽供热的应用

在某大型石油化工企业两套引进装置间建立蒸汽喷射式热泵供热系统．利用泵将2PE装置在生产过程中排放的副生蒸汽回收,将其能量品位提高后供至PP装置,满足其用汽压力和温度的要求。取得了显著的效益。     

Numerical study of heat transfer characteristics of semi-coke and steam in waste heat recovery steam generator for hydrogen production

With the steam obtained from the waste heat of high temperature semi-coke, the hydrogen production through gasification method is considered more commercially. The heat transfer of semi-coke bed and steam was investigated using an unsteady convection heat transfer three-dimensional model of semi-coke. The effects of particle size, steam flow and particle bed thickness on heat transfer characteristics were considered. The particle temperature calculated by three-dimensional model was in good agreement with the corresponding particle temperature of experiment. The heat transfer characteristics of single particle, the particle temperature, the amount of heat recovery and the heat flux were investigated. The results show that, in the first 10 min of the heat transfer of semi-coke bed and steam, the bottom particle temperature decreases rapidly, but the top particle temperature is almost unchanged. The heat transfer rate evolution of the single particle in different positions is revealed. The heat transfer rate evolution of the bottom particle is different from that of the middle particle and top particle, and the heat transfer rate evolution of middle particle is similar to that of the top particle. The particle size, the steam flow and the particle bed thickness have great influence on the heat transfer mechanism of semi-coke and steam, and the 7.5 kg/h is considered to be the best steam flow for heat recovery. The intrinsic heat transfer mechanism between semi-coke bed and steam was revealed.     

工业供热中汽汽再热器换热强化数值研究

为了强化工业供热中的汽汽换热,通过CFD技术对不同类型换热管的流动及换热特性进行了研究。结果显示：光滑壁面时管壁两侧的高、低温蒸汽的温度梯度沿着流向逐渐变化,对流换热逐渐增强;相比于光滑管,采用内波节管和内螺纹波节管时,高温蒸汽侧的温度梯度增大,而低温蒸汽侧的壁面温度梯度明显增大;采用壁面异型结构能够改变管壁内温度梯度,采用内螺纹波节管尤甚。采用内波节管和内螺纹波节管的平均Nu相比于光滑管显著提高,最大值分别提高了26%和30%。     

汽轮发电机气体冷却器性能试验研究

气体冷却器是汽轮发电机的重要设备之一。其传热与阻力性能将直接影响汽轮发电机的运行经济性和可靠性。为实现汽轮发电机气体冷却器的优化设计,对不同翅片间距的翅片管冷却器的传热和阻力性能进行了试验研究,得到了Re在3 000~190 000之间换热器翅片侧的传热和阻力特性,并分析了风速和翅片间距对气体冷却器传热和阻力性能的影响规律。研究成果对汽轮发电机气体冷却器的结构与性能优化具有重要的指导作用。     

联合循环电厂汽轮机供热运行的若干问题

国内某联合循环电厂由于汽轮机缺乏非设计工况下抽汽供热运行经验且需要参与电网调峰,经过对联合循环机组特性分析和现场运行数据的整理、优化,在保证机组安全的前提下,确定了汽轮机供热量和机组调峰能力,为指导运行人员操作和确定机组电网调峰能力提供了依据。     

不同管间距的垂直U型地埋管换热实验研究

对不同管间距的垂直U型地埋管进行了夏季工况连续实验,比对单U地埋管换热器不同管间距下的单位井深换热量、管群内土壤温度变化和系统运行情况,结果表明,管间距越大,单U换热器和土壤之间换热效果越好,管群内的热干扰越弱;管间距过小,系统内换热器的换热情况将恶化,导致不能长期稳定运行。     

Numerical study of heat and mass transfer in the plate methanol steam micro-reformer channels

Effects of geometric and thermo-fluid parameters on performance and heat and mass transfer phenomena in micro-reformer channels were investigated by mathematical modeling. The geometric parameters considered were the channel length, channel height, catalyst thickness and catalyst porosity, while the thermo-fluid parameters included wall temperature, inlet fuel temperature, fuel ratio and Reynolds number. The results of the modeling suggest that the methanol conversion could be improved by 49%-points by increasing the wall temperature from 200 °C to 260 °C. The results also show that the CO concentration would be reduced from 1.72% to 0.95% with the H₂O/CH₃OH molar ratio values ranging from 1.0 to 1.6. The values of parameters that enhance the performance of micro-reformer were identified, such as longer channel length, smaller channel height, thicker catalyst layer, larger catalyst porosity, lower Reynolds number and higher wall temperature.     

Design of geothermal steam supply systems in Iceland

The role of the geothermal steam supply system is to receive the geothermal fluid from the geothermal wells, separate the steam from the water and to deliver steam and/or water to a user of the thermal energy. It may be for direct use in any kind of an industrial process, such as drying, heating, cooling, etc., or it may be intended for electric power generation. The steam supply system delivers the fluid at a specified temperature, pressure and quality to the user.The steam supply system consists of wellheads, steam collection pipelines, nowadays in Iceland normally designed for two-phase flow of water and steam, steam-water separators, main steam/water lines, moisture separators, control valves, exhaust system, and effluent disposal equipment as needed and may include compressors and/or pumps for long distance transportation.Design criteria for the system depend on one hand upon the characteristics of the geothermal field, and on the other upon the intended use and required steam quality and economy. High enthalpy fields, for example, are capable of producing high pressure steam which is relatively economical when electric power generation alone is being considered. For such systems, high quality of the steam is of utmost importance.The paper gives a general overview of the steam supply systems in Iceland and describes the main features of the Nesjavellir steam supply system where the main emphasis was laid on high steam quality in order to prevent scaling in turbines, control valves and heat exchangers. New systems or systems needing restoration should be based on the same features.