1000 MW核电机组再循环管道振动分析及治理

为改善某1 000 MW核电机组再循环管道存在的振动及噪声,经过理论分析和现场实测数据对其进行研究发现支吊架设计不合理及气液两相流是造成管道振动的主要原因。通过支架改造和流体系统改造,有效地消除了管系的振动,确保了机组的安全运行,对核电机组其它管系振动原因分析及治理提供了参考。     

75 t/h燃气锅炉鼓风机送风管道振动分析及处理

75t/h锅炉鼓风机送风管道由于设计问题导致锅炉在满负荷运行时风道振动剧烈、噪音大,不能达到锅炉原设计额定运行参数。结合现场对75t/h锅炉鼓风机及送风管道进行改造,解决了风道振动较大的问题,最终经实际验证实现了锅炉满负荷运行。     

低压缸切缸改造后转子渐变式弯曲故障诊断

低压缸切缸改造是提高机组热电效率、降低热电耦合的典型方法。然而火电机组在参与调峰过程中工况的大范围变化、设计制造时未考虑切缸改造等因素,可能导致机组轴振的爬升。针对某厂切缸改造后的实际轴振超限案例,分析认为振动异常的原因为新低压转子运行中随着残余应力释放而发生渐变式弯曲故障,通过现场动平衡方法实现了降低振动幅度的目标。实践证明该方法有效解决了振动异常问题,为供热改造机组故障诊断与处理提供有益参考,具有重要的实际意义。     

高压锅炉中的内螺纹管的腐蚀与沉淀

前言在许多高压锅炉的设计中,要在所有的汽水回路里得到足够的质量流速是设计者难以做到的。增加下降管和上升管的流通截面可使质量流量增多,但这会使锅炉成本提高。为了在多种运行工况下不必靠较高的质量流速而能避免偏离核态沸腾(DNB),拔柏葛公司发展了一种内螺纹管,经过试验已在许多高压锅炉的炉膛内使用了这种内螺纹管。本文将讨论在已运行的高压锅炉上取样发现的内螺纹管的腐蚀和沉淀问题。     

引送风机节电降损的方案分析

通过对国华神木公司引送风机设计、运行工况的数据分析，得出引送风机电耗大，效率低的问题，论证了引送风机节电降损的几种改造方案及其可行性，并针对国华神木公司具体情况进行分析，提出了引送风机改造的可行性建议方案：     

脱硝还原剂液氨改尿素技术应用及优化

电厂烟气脱硝SCR系统脱硝还原剂采用尿素取代液氨已成为行业趋势,尿素具有与液氨相同的脱硝性能,且具有环保、无毒性和安全性高等优点。某电厂对烟气脱硝SCR系统实施液氨改尿素热解制氨工艺,本次改造的热解系统单套640kg/h的制氨量是迄今国内最大的,具有停留时间长、能耗大、运行费用高、调节范围大等难点。为此,在进行流场/温度场模拟的基础上,采用高温烟气换热方案代替电加热器方案,对运行模式和喷枪控制进行了调整。从运行后的数据来看,在锅炉满负荷(600MW)运行时,热解炉系统满足氮氧化物排放低于50mg/m³且氨逃逸低于3μL/L的要求,炉内尿素热解完全,无结晶出现。采用炉内气气管式换热器代替电加热器作为热源,每年可节省电费约570万元,不到半年即可收回投资成本。项目的顺利实施为尿素热解系统的超大型化应用积累了更多经验。     

QF-6-2型发电机前轴承的改造

针对ＱＦ－６－２型发电机组轴承设计不当，存在检修困难和机组振动问题，对发电机前轴承进行了改造。改造后，彻底解决了问题，确保了机组安全运行。     

哈尔滨第三发电厂600 MW机组循环水泵改造叶轮优化设计

哈尔滨第三发电厂两台600MW机组现场测试及调研的结果表明,循环水泵机组运行效率低于原型泵设计。对机组进行了技术改造,并利用CFD技术对改造前后叶轮进行数值分析比较,结果表明,改造后循泵振动小、流量大,2a多无检修,确保了电厂发电机组安全可靠、经济的运行。     

循环流化床锅炉放渣管膨胀节技术改造

中原大化集团公司动力厂安装了2台某锅炉厂设计制造的75t／h循环流化床锅炉，设计压力5．4MPa，设计温度450℃，承担着向集团公司合成氨、2套三聚氢胺装置供应蒸汽的任务，所以锅炉运行的稳定直接关系到整个集团公司的利益。锅炉于2002年9月点火运行，运行期间，因放渣管原因造成停车多次，给动力厂和集团公司造成很大经济损失。经过对锅炉放渣管出现的问题的分析研究，结合其他厂家的改进经验，提出了1套技术改进措施，并于2004年底进行实施，经过2005年运行实践，没再出现过放渣管损坏情况，稳定了锅炉的长周期运行。     

某国六柴油车用尿素箱支架断裂分析及优化

为解决某国六柴油车用尿素箱支架的断裂故障,利用Abaqus对该尿素箱支架进行应力分析和断口形貌电镜分析,确定支架断裂的原因为"L"形支架的长条孔、装车支架底部与"L"形支架连接处应力集中.根据受力状态进行优化,消除"L"形支架的长条孔,并加长装车支架.利用该车型实际运行路谱对优化前后的尿素箱支架进行振动试验考核,结果表...     

凝汽器杂项疏水的处理

电站热力系统中相当数量疏水管路接口排入凝汽器或扩容器,疏水排入的过程中涉及到流体动力、扩散、闪蒸及两相流等多种复杂问题。疏水处理不当往往会引起凝汽器内原热平衡的破坏,使凝汽器内凝结饱和温度提高,导致背压升高,影响机组出力;还会引起冲击、振动、热胀,造成冷凝管破损、壳体开裂等问题;严重时甚至还会损坏汽轮机叶片。但长期以来,国内外对这方面的理论研究较为鲜见,很难用单纯的理论计算方法来解决。该文分析了疏水排入的位置、能级和流速,提出了处理各种疏水的原则和方法,完善热力系统及凝汽器的设计,确保电厂安全可靠运行。图3表2参4     

Thermosiphon circulation in solar water heaters incorporating evacuated tubular collectors and a novel water-in-glass manifold

A study is reported of thermosiphon circulation in solar water heaters incorporating glass tubular evacuated collectors and a water-in-glass manifold of extremely simple design. The manifold is characterised by the absence of partitioning of the inner volumes of the absorber tubes into inlet/outlet channels and buoyancy effects are utilised to convey heat to a header pipe at the open end of the tubes. Solar energy input to the tubes has been simulated by electric heating. The thermosiphon system design is unusual in that there are no risers within the collector tubes, thus, the pressure head responsible for thermosiphon flow originates entirely from relatively short pipe runs between manifold and storage tank. Thermosiphon flow has been measured for a number of system designs and a wide range of operating conditions. The relative impedances of the system components has been evaluated allowing optimization of the system design. An investigation of the effect of withdrawal of hot water from the storage tank, with associated injection of cold water to the bottom of the tank, has illustrated that the self-regulating nature of the thermosiphoning system results in a large proportion of heat stored in the wate filled collector tubes being effieciently transferred to the storage tank, providing some water is drawn off intermittently.     

某核电机组疏冷器失效原因分析及改进措施

某核电机组常规岛热力系统设置外置式疏冷器,机组首次大修时发现疏冷器部分换热管及栅架板断裂、部分换热管存在磨损及泄漏现象。断口形貌显示换热管及栅架板为振动损坏。应用换热器相关的国内外准则进行分析,明确该疏冷器换热管损坏的根本原因为壳程凝结水流速过快,流体弹性失稳、旋涡脱落诱发管束振动,造成尾部换热管及栅架损坏。针对这种状况,采取控制流速、加装防振栅架等措施,确保不会发生流致振动问题,从而保证疏冷器安全运行。     

Ammonia and related chemicals as potential indirect hydrogen storage materials

Energy production and combating climate change are among some of the most significant challenges we are facing today. Whilst the introduction of a hydrogen economy has its merits, the associated problems with on-board hydrogen storage are still a barrier to implementation. Ammonia and related chemicals may provide an alternative energy vector. Besides ammonia and metal amine salts, some other ammonia related materials such as hydrazine, ammonia borane, ammonia carbonate and urea also have the potential for use as alternative fuels. These materials conform to many of the US DOE targets for hydrogen storage materials.     

Efficient numerical approach for simulating a full scale vertical ice-on-coil type latent thermal storage tank

The present research proposes a new efficient numerical approach to analyze the phase changes of a full scale vertical ice-on-coil type latent thermal energy storage (LTES) tank. Experiments were conducted to validate the proposed method. Most previous studies have been forced to adopt over-simplified assumptions in order to analyze a full scale tank because of the tremendous computer memory and long calculation time required. Usually only one tube has been analyzed to estimate the charging and discharging performance of the whole system, based on the assumption that this tube represents the whole LTES tank. The proposed method overcomes the drawbacks of the existing approaches by sampling a few tubes and interpolating the whole tubes. The number of tubes to be calculated is thereby significantly reduced while preserving high accuracy. The proposed method is validated by (1) comparison with a reduced full simulation of 20 tubes and (2) experiment.     

尿素热解制氨SCR脱硝技术在电厂的应用与优化

针对大唐清苑热电厂脱硝采用尿素热解制氨SCR系统,在分析国内已投运电厂采用尿素热解系统生产运行出现的问题的基础上,提出了解决及优化措施,供读者在今后设计中参考。     

Measurement and simulation of flow rate in a water-in-glass evacuated tube solar water heater

This paper evaluates the characteristics of water-in-glass evacuated tube solar water heaters including assessment of the circulation rate through single ended tubes. A numerical model of the heat transfer and fluid flow inside a single-ended evacuated tube has been developed assuming no interaction between adjacent tubes in the collector array. Flow measurement using Particle Image Velocimetry (PIV) has been undertaken to validate the numerical model. The experimental rig consists of a single full-scale tube coupled to a storage tank. A non-dimensional correlation has been developed of the circulation rate through a single evacuated tube mounted at 45° inclination over a diffuse reflector. Simulation results show that the natural convection flow rate in the tube is high enough to disturb the tank’s stratification and that the tank temperature strongly affects the circulation flow rate through the tubes. Circumferential heat distribution was found to be an important parameter influencing the flow structure and circulation rate through the tube, hence a separate correlation needs to be developed if a concentrating reflector is incorporated into the collector.     

带高压一级旁路的1000MW汽轮机不设高排逆止门的布置改进

论述了采用高压缸启动方式的带高压一级旁路的1000MW超超临界汽轮机不设高排逆止门的依据及其防止汽轮机甩负荷超速、高缸超温与进水的方法:一是在高压导汽管上加装通风阀,二是在冷再管上加装通往凝汽器的排汽管,三是在冷再管的低位加装能显示水位、自动报警及自动疏水的疏水罐。这种设计布置是带有高排逆止门原设计的改进。根据改进结果,可以得出具有防止汽机甩负荷超速、防止空转时汽机高压部件过热、防止汽机进水的完善功能,达到系统简单、安全适用、减少投资目的的结论。     

An efficient water conditioning system for land‐based abalone aquaculture

Data collected from a single grow‐out tank in an abalone farm in southern New Zealand has highlighted hygiene maintenance problems in the use of semi‐closed water conditioning systems for the aquaculture of New Zealand black foot abalone Haliotis iris. The data shows that semi‐closed systems can have high concentrations of un‐ionized ammonia, which is harmful to the animals. In this paper an alternative open flow‐through system is suggested where energy demand is limited by heat recovery at the grow‐out tank outlet. Using temperature data collected over 1 year, and a previously obtained expression for standing losses, a simple energy model is presented for an open system with heat recovery. To compliment the energy model, a function has been established for abalone production with respect to the concentration of un‐ionized ammonia and water temperature. The energy model and production function are combined to determine the impact of plant design and tank conditions on the economics of the operation for the southern New Zealand climate. It is demonstrated that temperature control is financially preferable to an open system with no temperature control, and estimates of optimum operating conditions are given. Copyright © 2004 John Wiley & Sons, Ltd.     

Experimental Study of Deposits Removal in Thermal Desalination Plants by the Thermal Shock Technique

Deposition of salts on heat transfer surfaces in thermal desalination plants can lead to operational failure. Scale removal can occur by applying a thermal shock, which is a sudden decrease in the heating process. The difference in thermal expansion between the heat transfer surface and the deposit layer plays a key role in the thermal shock process. The objective of this research is to determine experimentally the minimum temperature of the heating surface in desalination units, such that the thermal shock is still applicable. The minimum heating temperature is important for minimization of heat losses. An experimental setup has been designed and developed, and it consists of an oil tank in which oil is heated by electrical heaters. The heated oil is circulated by a gear pump to the steam generator, which contains the water to be desalinated, that is, a CaSO₄ solution, at atmospheric pressure. The water is heated and converted into steam by the hot oil leaving the salts behind, that is, the fouling layer, on the tubes of the steam generator. A thermal shock is applied when the asymptotic behavior is approached, such that the flow of the hot oil is suddenly stopped for a short period of time before resuming it again. The minimum heating temperature has been determined for two types of tubes: stainless steel and copper, and at a salt concentration of 2 g/L. The minimum heating oil temperature that allows the applicability of the thermal shock is 130°C when using copper tubes, and 140°C for stainless-steel tubes.