一种基于级内损失理论的排汽焓计算方法

凝汽式汽轮机低压缸排汽段通常处于湿蒸汽区,排汽焓值难以直接测量.以级内损失理论为基础,将各类损失划分为与容积流量相关的排汽损失、与湿度相关的湿汽损失和与理想焓降相关的其它损失;推导了其它损失的系数与低压缸理想焓降的二次关系式;在此基础上,根据湿汽损失与排汽焓的关系提出一种排汽焓计算方法.利用该方法计算某660MW超临界汽轮机组的低压缸排汽焓,并与实际运行数据进行了对比.结果表明,提出的方法计算精度较高,所需测点少,对排汽流量的测量或计算精度要求较低,可应用于机组日常运行时对排汽焓的测算.     

电站汽轮机低压缸排汽焓近似计算模型研究

凝汽式汽轮机低压缸排汽段通常处于湿蒸汽区,排汽焓值难以直接测量。提出一种汽轮机排汽焓的计算方法,以级内损失理论为基础,将各类损失划分为与容积流量相关的排汽损失、与湿度相关的湿汽损失和与理想焓降相关的其他损失。排汽损失由排汽容积流量决定;湿汽级焓降占总焓降的比例系数通过低压缸热力过程线中的相似三角形关系求出;根据速比与理想焓降的关系,将其他损失的系数简化成只与理想焓降有关的二次多项式。通过理论计算和量纲分析证明排汽流量的误差对计算结果影响较小。应用提出的方法,根据设计数据计算了不同厂家生产的不同容量级别汽轮机机组的低压缸排汽焓,并与设计值进行了对比。结果表明,该方法在设计数据条件下计算精度较高,证明了该方法的可行性,为现场的实际应用奠定了基础。     

新型节能背压式汽轮机研究

现有的背压式汽轮机机组由于没有低压回热加热系统,在电厂运行中经常不得不用大量压力较高的排汽加热补水。事例计算证明,这将引起甚大的热经济损失。为减少这种损失,提出了研发带有低压级组的背压式汽轮机机组的建议,可用其低压回热抽汽及排汽来加热低温补给水,在不增加进汽量条件下,高、中压机组可分别增发12%、20%以上。这将大大提升机组的经济性,对于我国节能减排战略的实施具有重要意义。     

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。     

1000MW超超临界汽轮机排汽焓和冷端能量损失模型

建立凝汽式汽轮机冷源损失热量和排汽焓的计算模型,实时分析负荷和机组状态对冷端损失、低压缸排汽湿度和凝汽器总体换热系数的影响规律。基于别尔曼公式的形式,提出凝汽器总体换热系数的经验预测公式。结果表明,冷端能量损失百分比随负荷增大而单调降低。冷端能量损失占机组总输入能量的48.4%,占总能量损耗的85%~88%。低压缸排汽焓随负荷增加而单调降低,排汽湿度随负荷增加而单调增大。低负荷下,低压缸排汽为微过热蒸汽;高负荷下,低压缸排汽为饱和湿蒸汽。凝汽器总体换热系数随负荷增加而单调增加,且正比于低压缸排汽流量。     

基于支持向量机的汽轮机排汽焓计算

为了在线计算汽轮发电机组的经济性,本文建立了基于支持向量机(SVM)的汽轮机排汽焓计算模型。本文先采集影响汽轮机排汽焓主要参数的历史数据以及排汽焓的历史数据,并进行数据预处理剔除明显的坏点,剔除坏点后的数据用于对支持向量机模型的训练和验证,得到基于支持向量机的汽轮机排汽焓计算模型。结果表明:基于支持向量机的汽轮机排汽焓计算模型能够有效的预测汽轮机的排汽焓,且误差在1%范围内,汽轮机排汽焓的预测值比实测值平均小10 kJ/kg左右。汽轮机排汽焓的预测值与汽轮机排汽焓的实测值保持着相同的变化规律。基于支持向量机的汽轮机排汽焓计算模型能够用于在线实时计算汽轮机低压缸的排汽焓。     

燃煤电厂低温省煤器节能效益分析

阐述低温省煤器节能原理,分析低温省煤器对锅炉、汽轮机以及凝汽器的影响,以CLN600-24.2/566/566型汽轮机组为对象,运用等效焓降法计算分析加装低温省煤器的节能效益。尾部烟道加装省煤器能有效提升汽轮机出力、降低汽耗率和发电煤耗率,是电厂热力系统节能降耗的有效方法。     

基于能量损失的低压省煤器系统节能效果研究

基于热力学第一定律的基本理论,以火电厂能量损失为研究对象,分析低压省煤器投入运行后对电厂各项能量损失的影响,建立了定功率条件下计算低压省煤器节能量的数学模型。该计算模型根据局部参数的测量就能较准确的评价低压省煤器的节能效果,简化了试验过程。将该方法应用在某国产330 MW机组上,并与热平衡图法和等效焓降法的计算结果进行了比较,证明了该方法的准确性。     

小机排汽对凝汽器喉部流场影响的研究

针对凝汽器喉部有低压加热器和汽动给水泵的小汽轮机排汽的布置形式,应用FLUENT计算软件,对某300MW汽轮机凝汽器的喉部流场进行三维数值模拟,分析凝汽器喉部出口流场的分布和能量损失系数的变化。结果表明:小机排汽的存在增大了喉部流场的不均匀性,在靠近小机排汽侧的出口截面又形成了两个局部低速区。小机排汽量从额定工况不断增加时,喉部的能量损失系数减小;反之,喉部的能量损失系数增大。小机排汽的入口位于低加以下时,排汽对喉部出口流场的影响较小,能量损失系数减小。该研究对于凝汽器喉部的完善化设计及改造具有一定的指导意义。     

汽轮机排汽焓动态在线计算模型的研究

针对现有的汽轮机低压缸排汽焓在线计算模型存在一定的局限性,提出了一种排汽焓在线计算新模型.该模型不必对低压缸湿蒸汽区进行计算,同时避开了流量测量,主要利用在线监测的温度和压力进行计算,所需测点相对较少,测点积累误差小.实例计算表明:新模型计算工作量小、精度高,完全能够满足工程计算的需要.     

Saturated steam process with direct steam generating parabolic troughs

The direct steam generation (DSG) in parabolic trough collectors is an attractive option regarding the economic improvement of parabolic trough technology for solar thermal electricity generation in the multi Megawatt range. The European DISS project has proven the feasibility of the direct steam generation under real solar conditions in more than 4000 operation hours. Within the European R&D project INDITEP the detailed engineering for a pre-commercial DSG solar thermal power plant with an electrical power of 5 MW is being performed. This small capacity was chosen to minimise the risk for potential investors.In regards to DSG solar thermal power plants, only steam cycles using superheated steam have been investigated so far. The paper will investigate the advantages, disadvantages, and design considerations of a steam cycle operated with saturated steam for the first time. For near term applications, saturated steam operated DSG plants might be an interesting alternative for power generation in the small capacity range due to some specific advantages:

• Simple set up of the collector field.

• Proven safe collector field operation.

• Higher thermal efficiency in the collector field.

浅谈蒸汽预热器的防振措施

蒸汽预热器用于垃圾焚烧炉中,通过向换热管中通入高、低压蒸汽凝结放热来加热送风机出口的冷风,将风温由室温提高到220℃左右.目前应用较为广泛.蒸汽预热器空气流速一般为7～10m/s,风速较高,在锅炉其他设备上发生过换热管束振动现象.蒸汽预热器采用换热管排方式设计,换热管布置较为紧凑,因此,在设计蒸汽预热器时需要考虑管束振...     

Effect of pollutants on biogas steam reforming

This study reports the influence of biogas poisoning on a Ni based catalyst working under steam reforming conditions (atmospheric pressure, T = 1073 K and H₂O/CH₄ = 2 mol/mol). A biogas stream composed by CH₄ and CO₂ with a ratio 55/45 vol.%, added with different chemical species (H₂S, hydrocarbons mixture and D5) as contaminants, was used as inlet gas stream.First, effect of poisoning on Ni catalyst were separately evaluated and the boundary concentrations for each contaminants were revealed (0.4 ppm, 200 ppm and 0.5 ppm for H₂S, hydrocarbons and D5 respectively) to assure Ni stable performances on time on stream (100 h at 50,000 h^?1 of GHSV). Successively, a comparison between Ni catalytic behaviors in presence of two combined poisoning in the biogas (H₂S + Hydrocarbons and Hydrocarbons + D5) was carried out.It was found that the effect of combined poisoning, even though it considered in moderate concentration, is harmful for Ni catalyst activity. Methane conversion on time on stream was reduced from 86% to 40% after 50 h, when the couple of poisoning Hydrocarbons + D5 was added to the inlet gas stream, while a lower deactivation pattern (about 73%) was leaded by couple H₂S + Hydrocarbons. Both poisoning mixtures promoted coke deposition on Ni catalyst surface (about ≥0.5 mgC/g_cat·h) independently by poisoning chemical characteristics probably due to adsorption/deposition of contaminants on catalytic sites.     

Concept on thermoeconomic evaluation of steam turbines

Concepts of exergoeconomic audits and evaluation of steam turbines are presented. In the first part of the work, an analysis based on the first and second laws of thermodynamics is applied to a power plant. The well-known procedures of “Exergy Cost Theory” and the “General Theory of Thermoeconomics” proposed by Valero et al. [V. Verda, L. Serra, A. Valero, Zooming procedure for the thermoeconomics diagnosis of highly complex energy systems, Int. J. Appl. Thermodyn. 6 (2) (2002) 75–83] are used. These methodologies allow the computation of exergy-cost and economic-cost of local products (P) and fuels (F) in each plant component (especially in steam turbines). The second part of the work consists of an evaluation and determination of the degree of entropy generation (ΔS_g) and power loss (ΔW) in a steam turbine stage (nozzle-bucket), under the detection of specific malfunctions. As it is well known, steam turbines can develop intrinsic malfunctions such as roughness, seal and leak clearances, erosion, and sedimentation. The main objective of this work is to assess the exergy-cost (fuel impact cost) due to the intrinsic malfunctions in a steam turbine stage.     

蒸汽凝结水密闭式回收系统中水抽汽喷射器的应用

介绍了密闭式蒸汽凝结水回收节能技术,及采用抽汽喷射器的新技术来回收乏汽。分析了此类喷射器的工作特点和节能意义,介绍了此类喷射器在实际中的使用情况。     

宝钢中压蒸汽管网疏水系统的节能研究

工业企业内的节能工作已经成为企业可持续发展的主题,作为能源消耗中的蒸汽系统,目前在宝钢内部的损失率居高不下。介绍了宝钢中压蒸汽疏水器的现状,通过试验对节能型疏水器与普通疏水阀的性能进行了对比,并对节能型疏水阀的经济性进行分析,并提出了宝钢中压蒸汽疏水系统改造方案。     

Ultra-supercritical steam turbine Turbosets-Best efficiency solution for conventional steam power plants

正(Continued from the previous issue)The materials are already applied in running steam power plants worldwide.Further effort is made to increase the temperature above 610℃.Based on the experience of Siemens with USC SPP from the 60-ies up to 100 MW,the application of austenitic alloys is not planned for thick walled components because of their physical properties,manufacturability and restricted component size.The current RD activities include also work packages for 700℃steam turbine materials for the near future.The chance for a successful design is seen by using the class of     

Direct contact condensation of superheated steam on water

Referring to the interaction of superheated steam (practically stagnant) with subcooled water (slowly moving) the results of an experimental research are presented and discussed. As foreseen in a theoretical investigation, the total thermal power (and consequently the total heat transfer coefficient) does not show an appreciable dependence on superheated steam temperature, so it can be practically evaluated by means of available correlations for saturated steam conditions. The direct contact condensation heat transfer coefficient is linked to the overall one and is slightly dependent on the degree of steam superheating, as experimentally confirmed.     

木质纤维素蒸汽爆破预处理技术的研究进展

介绍了蒸汽爆破预处理方法的研究进展、工艺路线及存在的主要问题,分析了处理强度、预浸条件、抑制物产生及脱毒处理、分子结构变化等对预处理效果(原料回收率、纤维素酶酶解率、糖得率)的影响,指出今后的发展方向是优化蒸汽爆破预处理和后续脱毒的工艺条件。     

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。