The traditional steam turbine model considers the boiler as an infinite heat storage unit without considering the changes in main steam pressure,resulting in the main steam flow rate being only a func-tion of valve opening.However,in the actual process,the main steam pressure will fluctuate due to changes in boiler thermal storage status and turbine valve opening,and is not in a constant state.There-fore,if the influence of main steam pressure is ignored,the simulation accuracy of the built model will be severely limited.This article considers the factors of main steam pressure changes on the basis of tradi-tional steam turbine models,establishes a more refined steam turbine model,and studies the impact of main steam pressure on the dynamic response of the steam turbine through simulation.
本文首先利用ICP-OES/MS电感耦合等离子发射光谱/质谱联用仪、傅里叶变换红外光谱仪以及X射线衍射仪等仪器检测了垃圾飞灰、危废飞灰以及两者耦合体的元素及化学物质组成.然后利用富氧高温熔融炉在不同氧浓度下进行了氧浓度对不同飞灰熔融温度以及重金属迁移影响的试验.结果表明,富氧气氛下随着氧浓度的升高,上述三种飞灰熔融温度先降低随后逐步升高,综合考虑采用富氧侧吹炉高温熔融处置飞灰项目,最佳氧浓度为25%.富氧气氛下,氧浓度的提高对于大部分重金属而言有利于其被固化,其主要原因在于氧化性气氛下有利于大部分重金属转化为高沸点氧化物.
为了弥补燃煤机组灵活运行条件下,脱硫系统本身的大时延、不确定性对脱硫过程的影响加剧问题,本文提出了一种基于变频浆液循环泵的脱硫控制策略,以提供更加及时的控制作用.同时,为了处理脱硫系统宽负荷运行时的时延特性和不确定性,提出了一种针对时延对象的更新高斯过程模型预测控制方法,并通过参数分析与仿真实验展示了该方法的性能.研究表明,本控制方案可以有效提高脱硫控制效率,从而降低能耗.
大粒径颗粒热解过程中颗粒内部的热传导过程通常不可忽略.为了更好地了解生物质颗粒热解过程中热质传递特性,本文考虑颗粒内部的热传导和斯蒂芬流的影响,建立了单个生物质颗粒热解的数值计算模型,分析了热解过程中颗粒内部的温度分布,得到了热解过程中颗粒与气体之间的表面传热系数.研究发现,粒内导热影响颗粒内部的温度分布,热解过程中,沿来流方向颗粒内不同位置温度有较大差异,加热气体温度为1173K时,粒径为10 mm的颗粒内部温差可达146.7 K;颗粒表面迎风侧最先开始热解,使得颗粒形状发生变化;热解过程中努塞尔数出现两个峰值,表面传热系数大于没有反应时的颗粒表面传热系数.
汽轮机发电机的轴振为机组可靠性和安全性埋下巨大隐患,降低振动值具有重大意义.本文对WX发电机轴振问题展开系统性研究:首先介绍设备情况及轴系结构,然后描述初始振动情况及其分析.基于此,制定降低振动的方案,并将降振结果在文中展示.实验结果表明,文中所提出的方案对于降低WX发电机轴振有着良好的效果,可作为该方面问题的一种有效解决措施.
实现干排渣机冷却风温实时测量与控制,对提高干渣机运行的经济性和可靠性具有重要作用.本文提出了一种基于声学的干式排渣机渣斗处冷却风温测量技术,并利用模极大值优化算法对声波信号进行降噪优化,提高信噪比,以保证冷却风温测量结果的准确性与稳定性.在此基础上,开发了干式排渣机渣斗冷却风温声学测量系统,并在国内某660 MW超临界机组进行了应用验证.结果表明,冷却风温的测量结果准确稳定,可跟踪机组负荷的变化,为干式排渣机经济运行优化提供了有力的检测技术支撑.
目前,为了保证火电深调的安全可靠性,不少配置6 组高压调节阀的汽轮机组,在低负荷运行时进汽方式都会切换至单阀控制方式;待升负荷运行至50％以上时,再切换至顺序阀控制方式.然而,机组切换过程中都出了不同程度的运行参数(负荷和主汽压等)波动问题.并且,现有研究几乎都是将该阀控方式切换时的参数波动问题根源,归结于两种配汽设计规律与阀组实际流量特性的不匹配问题.本文针对单顺序阀切换时的参数波动问题进行了理论分析,指出了单顺序阀切换过程中的阀门线性开关引起流量波动是产生波动的根源,并提出了一种汽轮机高调阀组进汽方式的非线性切换方法.理论计算结果证明:保持锅炉稳定条件下,该单-顺序阀切换方法理论上不会产生负荷波动.这对减小火电机组深调运行时阀控方式切换带来的参数波动问题具有重要的参考价值.
本文针对航空发动机涡轮叶片红外辐射测温方法中因受干扰因素多而导致的测温精度难以保证的问题,通过对曲面表面的发射率、双向反射分布函数、角系数等参数的测量,提出了一种用于三维弯曲表面的测温修正方法.通过实验室实验,并与典型位置上热电偶测温结果对比,测量修正后温度的误差稳定在1％以内,验证了本文所提修正方法的可行性,为涡轮叶片气动传热试验技术的提升和我国航空发动机等重大装备的研制提供支撑.
为进一步提高喷雾闪蒸海水淡化系统的能源效率,对耦合太阳能集热的多级喷雾闪蒸系统进行了热量和?经济分析,研究了太阳能热量变化对系统性能的影响.通过分析不同参数对能量变化的影响,得到相应?经济成本值的变化规律.研究结果表明,较高的顶值海水温度和流量增大了系统的生产率,从而提高了热回收效率,为热回收过程提供了更多的能量.生产率的变化有效地反映了太阳能辐射随季节的变化,在一年中阳光最少的一天,最小生产率约为峰值生产率的34％～38％.当运行级数为10,TBT =338 K,d =500 μm,Tcw,in =298 K时,系统所产生的?损最小,其单位?成本值为167.63$/kJ.单位?损成本率越低,所产生的?损越大,可以通过降低冷却水的输入温度来提高系统的运行效率以减少能量的损失.
航空发动机压气机在运行过程易发生喘振现象,危及发动机寿命.为达到提高VSV机构的运行可靠性以及降低发动机能耗等目的,满足整机台架试验要求.本文搭建了某型压气机VSV机构油压驱动试验台,采集不同工况下VSV机构油压驱动力,得到了常规与极限速度下油压驱动力数据,给出了VSV机构油压驱动力变化规律.试验结果表明:常规速度下,速度变量对油压驱动力几乎没有影响,行程变化工况下到达上止点时,油压驱动力会出现阶跃现象,对压气机VSV机构工作过程中驱动力预测和规律变化以及针对发动机压气机系统能耗、效率优化研究有一定的工程意义与参考价值.
管路布局优化是降低燃气轮机管路损失的重要手段,本文提出了一种燃气轮机不规则管路布局参数的优化设计方法.从燃气轮机外部抽气管路出发,建立了具有复杂布局走向的不规则多管路的参数化建模方法.分析了管路布局参数对管路损失的敏感性.综合燃气轮机考虑流量分布,温度与压力分布等多个目标.基于遗传优化算法,获得对外部管路布局参数优化设计优化结果.优化后的管路设计在规定约束优化空间内做到了损失的显著下降,为重型燃气外部抽气管路设计提供了参考.
印刷电路板式换热器不同通道型式的传热和流动特性存在明显的差异,本文基于兆瓦级超临界二氧化碳布雷顿循环发电应用条件,采用数值模拟方法计算印刷电路板式回热器直通道和Z通道的传热和流动特性,并且分析其存在差异的原因,获得了直通道和Z型通道换热器的传热特性、流动特性、速度场、温度场和热流密度分布,Z通道传热能力和流动压损均大于直通道,分析其原因是Z型通道的局部高流速、湍流效应和周期性扰动现象所致.
为了推动机械制造企业实现碳达峰碳中和目标,提高企业碳减排规划能力,本文以某机械工厂为场景,通过碳排放源识别和碳核算,分析企业资源禀赋、低碳技术发展等多重因素,提出企业碳减排总体路径,并制定实现零碳工厂的规划方案.通过对近期和中远期的各减排措施的减排量进行预测,得出研究对象在2050 年左右可实现零碳工厂的结论.本研究为实现零碳工厂进行了理论探索,为类似机械制造企业实现零碳工厂提供思路和参考.
当前,为了提高汽轮发电机组灵活运行时经济性,通常需要进行滑压运行控制曲线的优化.尽管汽轮机的高调阀进汽控制和运行背压是两个相对独立的过程,但两者会分别从冷、热两端影响其最优运行主汽压;尤其是在实际工程实施方面,难以实现对冷-热端耦合因素的全方位兼顾.本文在结合一台机组的实际运行情况、特点及需求的基础上,提出了一种考虑冷-热端因素耦合的汽轮发电机组滑压运行综合优化方法,依次对该机组的流量特性曲线、滑压运行控制曲线及运行背压控制曲线开展了相应的优化工作,取得了良好的实际应用效果.这对机组节能降耗的潜力得到最大程度挖掘,具有重要的工程应用价值.
混合动力系统采用轴带电机再生制动来吸收制动能量实现快速制动,但制动电阻的选型和控制分析需要大量的计算和校核.针对此问题,对混合动力船舶制动过程中螺旋桨负载的转矩随转速变化的特性进行仿真分析,提出基于轴带电机最大转矩电流比(MTPA)控制的制动控制策略和基于该控制方式的制动电阻选型过程、选型方法并进行仿真验证.仿真中轴带电机以MTPA控制方式实现了电磁转矩一直保持其最大转矩的快速制动;经仿真对比,小于等于5Ω的制动电阻选型方案能够满足目标船制动能量消耗需求.所形成的制动电阻选型及验证方法,能够在装船前对该关键部件与船舶的适配性进行很好地优化与验证,对于新型混合动力推进系统船舶关键部件的设计具有指导意义.
Different from the common piezoelectric energy harvester in which elastic beams are centrally symmetrically arranged under the bluff body, this paper proposes an eccentric arrangement of elastic non-centrally symmetrical connection under the D-shaped bluff body to improve the output power of the piezoelectric energy harvester. The mathematical model of the energy harvester is established by the distributed parameter method, and the correctness of the model is verified by experimental comparison. The effects of wind speed, eccentric distance, external load resistance value, and the length and mass of the bluff body on the output power and the starting wind speed of the energy harvester are analyzed. The results show that the output power of the energy harvester increases with the increase of the flow velocity and the eccentricity, and the length of the bluff body and the load resistance both have optimal values, so that the output power of the energy harvester can reach a maximum of 3.608 mW. According to the analysis of the results, the structural parameters of the energy harvester were changed to further optimize the performance of the energy harvester, and the maximum output power was increased by 39.8%.
In order to study the effects of pigment near-surface distribution on the emissivity of infrared camouflage coatings, a two-layer radiative transfer model consisting of pigment dopant layer and binder model was proposed. The absorption and scattering characteristics parameters of individual circular flake pigment particles at near-surface distribution were calculated by time-domain finite difference method, while the apparent spectral emissivity of the coatings was calculated with the Kubelka-Munk theory. The effects of the pigment near-surface aggregation, volume fraction, geometric dimensions on the emissivity were discussed. The results show that the coating emissivity with pigment near-surface aggregation distribution is lower than with at uniform distribution. The infrared emissivity of the camouflage coatings can be reduced by reducing the particle thickness, doping thickness, and increasing the doping volume fraction and number density.
The timely purification of indoor air during the normalization of epidemic management has become an important task to ensure people’s safety and health. In order to solve this problem, based on the necessary devices in the air conditioning system and the air disinfection device based on thermal coupling corona discharge with good disinfection effect, this paper studies a sterilizable plenum box, which can realize both ventilation and disinfection functions in the air conditioning system. In this paper, CFD technology is used to evaluate the comprehensive effect of pressure stabilization and disinfection of the sterilizable plenum box according to the different number, shape and size of the electrode plate of the sterilizing device, and the optimal design scheme of the sterilizable plenum box is given. The results show that when the number of plates is 6, the shape of plates is 1/4 round, and the width of plates is 114mm, the comprehensive effect of disinfection and ventilation in the plenum box is the best.
Through use of the panel safeguard supervisory system（PSSS） of the coal-fired boiler in power plant, the endothermic deviation coefficient of the heating surface along the width direction of the boiler is determined, and an operation optimization adjustment technology to guide the operation of boiler is then proposed based on the analysis of the endothermic deviation coefficient in this paper. The single factor comparative test of the endothermic deviation coefficient in PSSS system are carried out under tangential combustion and opposed combustion modes. It is found that the endothermic deviation coefficient is capable of characterizing the change of combustion in the boiler, which is consistent with the theoretical results. Based on the calculation and monitoring results of PSSS system, the reasonable adjustment of boiler operation mode can effectively reduce the heat absorption deviation along the width and depth of furnace, avoid pipe explosion or forced parameter reduction operation due to excessive pipe wall temperature deviation, and improve the safety and economy of unit operation. The combination of this technology with conventional combustion optimization and adjustment technology will have great application prospects in coal-fired power plant.
As an energy medium widely used in the industrial field, the measurement instruments for the transmission process of steam are uneven, and the flow state changes are more complex. The system simulation preview can be realized by building the pipe network model, providing theoretical support for optimizing operating parameters. Based on the mass and energy balance, the thermal and hydraulic losses of the steam pipe network were systematically analyzed and a matrix pipe network model was constructed. The temperature interpolation was adopted in the online solution process, That is, the hydraulic and thermal models were solved alternately over time. Finally, compared with the actual operation data of an industrial park, the parameter error was mostly within 5%, which meeted the accuracy requirements of engineering calculation and had practical application value.
