回汽保护控制下舰用蒸汽动力系统响应规律

回汽保护是缓解蒸汽动力舰船紧急减速时汽包压力骤升幅度、提高舰船机动性的有效措施。建立增压锅炉、主汽轮机、调节阀等设备模型,集成了回汽保护系统仿真模型,并应用试验数据对仿真模型进行了校验。对不同回汽保护控制条件下蒸汽动力系统响应规律进行仿真研究,研究结果表明:倒车调节阀开度越大、开阀时间越短,汽包压力骤升幅度越小,回汽保护效果越明显;倒车调节阀开度越大,冷凝器喉部最高温度越高,而开阀时间对于冷凝器喉部最高温度无明显影响。     

抽汽调节阀汽流激振原因分析及对策

高温高压汽轮发电机组,由于一抽抽汽疏水管大量积水,当一抽调节阀开度为33%时,一抽抽汽压力到达42.5 MPa投入管网,蒸汽与一抽管道积水冷热交换,一抽管道部分积水蒸发急剧膨胀,快速形成冷热交换蒸汽汽流漩涡,一抽管道逆止门来回波动,阀蝶受蒸汽汽流涡动产生剧烈激振,一抽调节阀阀杆连接的2个关节轴承拉长损坏。增加一个一抽疏水口管道,一抽抽汽投入后没有出现一抽调阀剧烈波动,但是一抽调阀阀座垂直振动烈度数值严重超标。通过频谱分析得出:一抽调节阀阀座垂直测点振动烈度主要有73 Hz频率分量,当一抽阀蝶关小时,一抽阀蝶受到蒸汽汽流涡动冲击,蒸汽对阀蝶产生强烈汽流激振。针对以上情况,对大流量一抽调节阀座结构形式进行比较分析探讨,最后采用一抽钟罩阀结构形式,一抽调节阀汽流激振问题得到了圆满解决。     

一种带补汽蒸汽透平的调速控制

结合仪征化纤2#PTA装置的蒸汽透平控制,对升速及机组运行模式之间的切换进行了阐述.对自产低压和超低压蒸汽补汽的引入做了说明.该蒸汽透平的转速主要是通过速度PID输出3分程控制机组进汽阀、旁通阀及低压补汽旁通阀采控制实现.     

丙烷脱氢装置汽轮机的在线清洗研究

汽轮机是丙烷脱氢装置的关键设备之一,长期运行后出现叶轮结垢现象,导致轮室压力上涨、主汽阀全开,严重时转速不受控制地下降、轴位移上涨。参考饱和蒸汽压力-温度曲线和相关装置在线清洗的经验,在汽轮机正常运行负荷下,进行在线清洗。经过3次尝试后,摸索出最佳清洗条件。在蒸汽温度为271℃、蒸汽压力为4.0 MPa时,叶轮结垢能够被有效地清除,轮室压力从3.7 MPa下降至2.0 MPa,主汽阀开度从100%下降至70%,轴位移从0.2 mm下降至0.005 mm,蒸汽消耗量从100 t/h下降至90 t/h。清洗之后,汽轮机恢复至初始开工的运行状态,有效地提高了装置运行效益,消除了设备运行安全隐患。     

汽轮机进汽和抽汽流量异常增大原因分析与处理

某抽汽凝汽式汽轮机大检修后,进汽调节阀开度异常增大,抽汽量明显增加。通过试验与检修发现,抽汽逆止阀内漏,抽汽管网蒸汽进入汽轮机内,使抽汽口处压力升高,导致汽轮机效率降低,造成进汽与抽汽流量异常。对抽汽逆止阀及其执行机构进行检修,调整逆止阀阀杆初始位置,汽轮机恢复正常。     

汽轮机进汽缸内复杂流场的三维数值分析

为弄清汽轮机进汽缸内的流动细节,找到导致调节汽阀运行不稳定的原因,采用SIMPLEC算法对某型汽轮机进汽缸内调节汽阀在工作开度下的流场进行了三维可压缩黏性数值分析.研究结果表明,调节汽阀左右两侧开度的较大差异导致的流场不对称,主控通流能力、流动特性和稳定性的喉口部位流场的剧烈变化,阀碟底部产生的空穴区等是造成调节汽阀振动的主要原因.     

不同放汽阀流量特性对弹射过程的影响规律

研究对象为某型蒸汽弹射装置,建立了系统的热力过程数学模型和飞机的力学模型,建立弹射装置的仿真模型并对其进行了可靠性验证,对分别选用快开阀、线性阀、抛物线阀、对数阀的蒸汽弹射装置动态性能进行了仿真研究。仿真计算结果表明：当其他参数均一致,选用具有不同流量特性的阀门时,弹射耗汽量相差不大,均在560 kg左右,弹射过程时间：快开阀<线性阀<抛物线阀<对数阀,且弹射时间均在3 s以内,选用线性阀与抛物线阀时,汽缸内压力曲线更为平稳,飞机最大加速度也较小,分别为40.97与42.80 m/s²,飞机最终起飞速度均大于75 m/s。     

工艺蒸汽加热网络与蒸汽系统的集成优化

蒸汽动力系统作为过程工业的重要组成部分,由蒸汽系统、分配系统和蒸汽加热网络组成。文中提出对蒸汽系统、分配系统和蒸汽加热网络进行集成优化。首先通过夹点分析对工艺蒸汽加热网络进行优化匹配,得到各等级蒸汽需求量及凝结水回收参数;然后根据建立的蒸汽系统和分配系统的运行优化模型得到产汽及分配方案。通过对某化工厂的能量利用系统进行集成优化,得到的优化方案与传统设计方案相比,锅炉燃料消耗量减少16.38%,同时系统所需要的外界补给水量减少16.27%。提出的集成优化方法对蒸汽动力系统的设计优化具有一定的指导意义。     

一种热泵供汽控制系统的改进方案

针对传统PID控制在热泵供汽系统中的阀门动作迟滞、反应速度慢以及二次蒸汽利用率低的缺陷,提出了一种新型的纸机热泵供汽系统.该控制系统在西门子原有PID控制模块FB42的基础上加入模糊控制器,按照一定的模糊规则对PID控制器的比例参数和积分参数进行快速修正.以此方法来控制热泵系统中压力控制回路阀门的开度,可以使系统中阀门开度变化平稳、快速,且能有效减少次品量,提高蒸汽利用率,达到减少能耗的目的.     

蒸汽动力系统经济成本分摊及运行优化

石化企业蒸汽动力系统的任务是为工艺提供蒸汽和动力,蒸汽动力系统的汽电成本计算或分摊一直是工业界和学术界关注的焦点问题。文中基于经济学原理,通过建立设备及系统的质量平衡、能量平衡、平衡及经济平衡、成本补充方程,对某石化企业蒸汽动力系统进行了成本计算,得出了蒸汽动力系统各流成本,给出了确定汽电需求下的总成本并进行了分析,并以总成本为目标,对运行方案进行了优选。所得结果对于对决策人员实施运行优化及系统更新改进具有一定的指导意义。     

工业汽轮机的特性与改造

本文通过对蒸汽轮机的流场进行校核,介绍了冲动式汽轮机与反动式汽轮机的工作原理及特点,阐述了流场校核的方法及其重要性.     

High-efficiency and pollution-controlling in-situ gasification chemical looping combustion system by using CO2 instead of steam as gasification agent

Using CO₂ as gasification agent instead of steam in in-situ coal gasification chemical looping combustion (iG-CLC) power plant can eliminate energy consumption for steam generation, thus obtaining higher system efficiency. In this work, a comparative study of iG-CLC power plant using steam and CO₂ as gasification agent is concentrated on. The effects of steam to carbon ratio (S/C) and CO₂ to carbon ratio (CO₂/C) on the fuel reactor temperature, char conversion, syngas composition and CO₂ capture efficiency are separately investigated. An equilibrium carbon conversion of 88.9% is achieved in steam-based case as S/C ratio increases from 0.7 to 1.1, whereas a maximum conversion of 84.2% is obtained in CO₂-based case with CO₂/C ranging from 0.7 to 1.1. Furthermore the effects of oxygen carrier to fuel ratio (φ) on system performances are investigated. Increasing φ from 1.0 to 1.4 helps to achieve char conversion from 75.9% to 88.9% in steam-based case, by contrast the char conversion can achieve 66.3%-84.2% in CO₂-based case within the same φ range. In terms of iG-CLC power plant, recycling partial CO₂ to the fuel reactor improves the overall performance. Approximately 3.9% of net power efficiency are increased in CO₂-based plant, from steam-based plant. Higher CO₂ capture efficiency and lower CO₂ emission rate are observed in CO₂-gasified iG-CLC power plant, expecting to be 90.63% and 85.18 kg·MW^-1·h^-1, respectively.     

装置蒸汽动力系统与热电厂运行同步优化

石化企业装置蒸汽动力系统通常独立设计和操作,忽视了与热电厂蒸汽动力系统的联系。热电厂蒸汽动力系统通常在固定的蒸汽和电力需求下进行优化,忽视了与装置蒸汽动力系统的联系。为实现石化企业蒸汽动力系统的全局优化,本文提出了用于装置蒸汽动力系统与热电厂运行同步优化的方法。首先使用热电厂透平和锅炉的设计及运行数据回归得到设备模型系数,依照现有结构建立热电厂蒸汽动力系统约束。然后以装置蒸汽动力系统设计和操作灵活性为区分,将装置分为三类：第一类装置蒸汽和电力需求无法调节;第二类装置可以通过减温减压调节蒸汽需求;第三类装置既可以通过减温减压调节蒸汽需求,也可以通过驱动选择调节热电需求。装置透平模型参数采用文献值,通过采集各类装置蒸汽和电力需求等数据建立装置蒸汽动力系统约束,最后通过热电厂与装置蒸汽和电力的连接关系建立耦合模型。耦合模型以年度费用为目标函数,其中包括热电厂运行费用以及装置透平和电机的年度投资费用,通过优化求解得到热电厂设备负荷分配方案以及装置蒸汽动力系统设计方案。通过算例论证了同步优化方法的可行性,与独立优化相比,同步优化降低年度费用451万美元。     

基于等效电法的钢铁企业蒸汽系统多目标运行优化策略

针对钢铁企业蒸汽系统汽源设备多、能源品种多的特点,以某大型钢铁企业实际运行的蒸汽系统为背景,运用等效电方法对蒸汽系统的能量转换作出科学分析,采用数学规划方法,建立多目标的混合整数非线性规划模型（MINLP）。采用分步优化方法,先以蒸汽系统小时能源总成本最低为目标,将得到的结果乘以松弛系数建立成本约束并以(火用)效率最高为目标,利用LINGO软件求得多目标-约束优化模型的全局最优解,再通过改变松弛系数得到一组Pareto前沿。最后与单目标优化和多目标遗传算法结果相比较,证明分步优化方法所得的结果是可行的综合最优结果,能够实现低成本和高(火用)效率的双目标,并为生产调度提供依据。     

Integration of a Gas Fired Steam Power Plant with a Total Site Utility Using a New Cogeneration Targeting Procedure

A steam power plant can work as a dual purpose plant for simultaneous production of steam and elec-trical power. In this paper we seek the optimum integration of a steam power plant as a source and a site utility sys-tem as a sink of steam and power. Estimation for the cogeneration potential prior to the design of a central utility system for site utility systems is vital to the targets for site fuel demand as well as heat and power production. In this regard, a new cogeneration targeting procedure is proposed for integration of a steam power plant and a site utility consisting of a process plant. The new methodology seeks the optimal integration based on a new cogenera-tion targeting scheme. In addition, a modified site utility grand composite curve （SUGCC） diagram is proposed and compared to the original SUGCC. A gas fired steam power plant and a process site utility is considered in a case study. The applicability of the developed procedure is tested against other design methods （STAR？ and Thermoflex software） through a case study. The proposed method gives comparable results, and the targeting method is used for optimal integration of steam levels. Identifying optimal conditions of steam levels for integration is important in the design of utility systems, as the selection of steam levels in a steam power plant and site utility for integration greatly influences the potential for cogeneration and energy recovery. The integration of steam levels of the steam power plant and the site utility system in the case study demonstrates the usefulness of the method for reducing the overall energy consumption for the site.     

不同运行环境蒸汽动力系统特性

环境温度和压力作为蒸汽动力系统的自然工作条件,对于动力系统尤其是增压锅炉装置运行的安全性及经济性有重要影响。建立了蒸汽动力系统仿真模型,对不同环境条件下的动力系统运行特性进行仿真研究。结果表明：环境温度越高,涡轮增压机组辅机功率及蒸汽消耗量越大,动力系统燃油消耗量越大;环境压力越低,涡轮增压机组辅机功率及蒸汽消耗量越大,动力系统燃油消耗量越大;动力系统负荷越低,辅助汽轮机在为压气机提供功率时所占的比重越大。     

Design of a small solar-powered desalination system

A design is presented for a solar/thermal system configured to power a reverse osmosis (RO) desalination unit to produce 7000 gallons of fresh water in an eight hour period. A field of line-focus tracking solar collectors is used to heat a high pressure liquid-vapor water storage tank supplying two compound reciprocating steam engines, one direct-connected to the RO high-pressure pump and the other to an electric generator for auxiliary power. An auxiliary heating loop with an oil-fired boiler is also used to supply the steam engines.The system operates in either all-solar, all-oil, or mixed solar/oil modes. Primary operating mode is assumed to be a mixed solar/oil mode in which the oil-fired boiler is used only to prevent shutdown of the RO system during the course of a partly sunny day. In this mode, the RO system does not come on line in the morning until the solar collector field has brought the high-pressure storage tank to a point near maximum operating pressure. Thereafter, the oil-fired boiler comes on automatically whenever the storage tank is drawn down to a pressure near minimum full-power operation (due to inadequate or intermittent insolation) and remains on, supplying the steam engines, until the solar collectors have again brought the storage tank to the high-pressure cutoff.In the all-solar mode, the system continues to operate at reduced power as storage tank pressure drops below the point at which the oil-fired boiler would otherwise come on. A portion of the RO system is shut down to maintain pressure in the remainder.The all-oil mode is used whenever fresh water is required during non-sunny periods, or to increase fresh water production in sunny periods.     

Performance analysis of integrated biomass gasification fuel cell (BGFC) and biomass gasification combined cycle (BGCC) systems

Biomass gasification processes are more commonly integrated to gas turbine based combined heat and power (CHP) generation systems. However, efficiency can be greatly enhanced by the use of more advanced power generation technology such as solid oxide fuel cells (SOFC). The key objective of this work is to develop systematic site-wide process integration strategies, based on detailed process simulation in Aspen Plus, in view to improve heat recovery including waste heat, energy efficiency and cleaner operation, of biomass gasification fuel cell (BGFC) systems. The BGFC system considers integration of the exhaust gas as a source of steam and unreacted fuel from the SOFC to the steam gasifier, utilising biomass volatilised gases and tars, which is separately carried out from the combustion of the remaining char of the biomass in the presence of depleted air from the SOFC. The high grade process heat is utilised into direct heating of the process streams, e.g. heating of the syngas feed to the SOFC after cooling, condensation and ultra-cleaning with the Rectisol^® process, using the hot product gas from the steam gasifier and heating of air to the SOFC using exhaust gas from the char combustor. The medium to low grade process heat is extracted into excess steam and hot water generation from the BGFC site. This study presents a comprehensive comparison of energetic and emission performances between BGFC and biomass gasification combined cycle (BGCC) systems, based on a 4th generation biomass waste resource, straws. The former integrated system provides as much as twice the power, than the latter. Furthermore, the performance of the integrated BGFC system is thoroughly analysed for a range of power generations, ～100–997 kW. Increasing power generation from a BGFC system decreases its power generation efficiency (69–63%), while increasing CHP generation efficiency (80–85%).