基于组件技术的火电厂热力系统的实现

由于火电机组系统复杂，设备多，利用计算机组件编程技术开发出具有共同特性的设备组件，不仅可以解决复杂系统的实现，而且具有很好的继承性，便于系统的扩展。利用组件编程的思想开发了热力系统中各设备的通用组件模型。采用完成的组件能根据不同的机组热力系统结构，构成实际的热力系统图，设备的参教可以通过其内部定义的属性来读取或赋值，组件之间可以利用内部定义的成员方法来相互通信，从而完成机组的热经济性计算。组件思想大大提高了热经济性分析软件的开发速度，降低开发成本，使得软件开发扩展性强，灵活性高，代码重用率高。     

基于单元炯分析模型回热系统节能诊断

电厂运行的经济性已经日显重要。回热系统作为电厂热力系统中的主要系统之一,它对全厂的经济运行产生着很大影响,因此,回热系统经济性分析是电厂节能工作中的重要部分。以某热电厂机组的回热系统为研究对象,给出了系统的单元划分方法和通用的单元炯分析控制体模型,导出了通用的性能评价指标计算式,以实际计算说明了基于单元炯分析模型的节能潜力诊断方法。该方法可以找出系统能量损失的关键部位,为电厂热力系统节能分析提供一条依据。     

火电机组热经济性通用分析模式的开发思路

通过对热经济性通用分析模式研究现状的分析,提出在矩阵算法下利用模块化的思想,把热力系统按照系统组成的最小部件类型划分模块,并在Delphi平台上把模块做成一个一个单一的组件。针对任意的热力系统,使用组件以堆积木的方式完成系统的组态,实现组态同时自动生成平衡方程的一种新型的热经济性通用分析模式。     

基于EASY5仿真平台的火电厂热力系统仿真模型

采用模块化建模方法,合理划分部件,引入容积模块,使用状态变量解决系统中压力-流量之间的耦合关系,避免迭代计算,提高计算效率。以EASY5仿真软件为平台,开发了火电厂机组中各主要部件的模块库,方便不同结构系统模型的搭建。以某电厂1号机组为对象,结合热力系统的特点建立了机组热力系统仿真模型,对机组在额定工况下的特性进行了仿真分析,并与已有的试验数据对比,验证了仿真模型的有效性;在此基础上,进行了机组的动态特性仿真,获得了机组的瞬态响应特性,为机组控制性能的改善提供参考。     

基于单元(火用)分析模型回热系统节能诊断

电厂运行的经济性已经日显重要。回热系统作为电厂热力系统中的主要系统之一,它对全厂的经济运行产生着很大影响,因此,回热系统经济性分析是电厂节能工作中的重要部分。以某热电厂机组的回热系统为研究对象,给出了系统的单元划分方法和通用的单元分析控制体模型,导出了通用的性能评价指标计算式,以实际计算说明了基于单元分析模型的节能潜力诊断方法。该方法可以找出系统能量损失的关键部位,为电厂热力系统节能分析提供一条依据。     

基于结构特征矩阵的电厂热力系统通用矩阵模型

提出了一个适用于计算机软件开发的电站热力系统通用矩阵模型,并编制了程序,通过实例计算验证了模型的正确性.该模型基于热力系统的结构特征矩阵和回热加热器的"通断系数",对加热器的结构特征进行了高度的抽象,全面考虑了回热加热器类型、换热器效率以及各种辅助汽水等因素.该矩阵模型结合了组态思想,算法可靠,通用性强,适用于大型火电机组的热经济性分析计算,为电厂实时监测和分析软件的开发提供了方便的工具.     

热机系统仿真中一种通用介质容积模型的建立

在燃气轮机等热机系统的仿真中，气体属性环节的处理及其快速准确计算是一个普遍遇到的问题。本文根据容积法系统建模的思想，建立了一种通用介质容积模型。这种介质容积模型实际上是一个能量和质量的存储器，其内部视为均匀场，即处处具有相同的热力状态，通过流入流出的流量差而引起其间参数变化。它由状态转变模块和介质模块两部分组成，包涵了质量和能量守恒关系，能够准确地反映瞬态过程中各主要参数的变化，满足进行实时仿真对模型的要求，同时具有通用性。使用容积法建立的热机模型，可以避免流量和压强关系的迭代计算，同时对计算量的要求又在合理的范围内。在仿真软件Modelica的支持下，利用这种通用介质容积模块建立了燃气轮机模型，并进行动态仿真。     

通用锅炉热力计算软件的系统建模研究

通用锅炉热力计算软件的开发具有急切的工程需求。笔者提出了锅炉传热的抽象认识模型，应用面向对象技术，以统一建模语言UML设计了通用热力计算软件的系统模型，并给出了软件的成功开发实例。     

基于质量单元的联产机组热电分摊算法

运用工程热力学基本原理,以联产电厂热力系统为研究对象,通过对热力循环特性的详细分析,将其划分为不同的质量单元.建立了主辅循环各质量单元的单元进水系数通用矩阵方程,对联产电厂中循环间的功率、流量和热量的分配关系进行了分析,揭示了联产抽汽循环中热、电存在的实质.经数学推演建立了基于质量单元的联产电厂热、电分摊和联产产品热力成本的计算模型,并对某国产600WM抽凝机组进行实例计算,说明该计算方法简单实用,计算结果可信.     

PI实时数据库在株州电厂SIS系统中的应用

株州电厂选用了工业上应用比较成熟的PI实时数据库系统作为该厂SIS系统的支撑平台。目前,株州电厂SIS系统已经通过现场测试、验收和移交,并投入商业运行,系统运行状况良好。文中结合株州电厂SIS系统的建设,介绍了PI实时数据库系统的功能和特点,并阐述了PI实时数据库在SIS项目中的具体应用与实践。图2参5     

电厂热力系统能效分布矩阵方程式及其应用

提出了虚拟热力系统的概念,将纷繁复杂的实际热力系统用一个系统结构和热经济性指标不变,但参数发生变化的单一主系统——虚拟热力系统所替代。并在此基础上,构造了火电机组能效分布矩阵方程,该矩阵方程直接和热力系统结构一一对应,且有表征机组热经济性指标的矩阵元素,有效克服了目前新兴的热经济性矩阵分析方法需要联立其它方程才能求解系统最终热经济性指标的缺陷,具有通用性、精确度和易于程序化的特点。算例说明了方法的有效性。     

新型二甲醚用双液体热力泵的研究

在分析二甲醚(DME)物化特性的基础上,提出了燃用DME对供油系的特殊要求。详细介绍了既能保持DME处于液态,又能将DME泵送到高压喷油泵中的新型二甲醚钢瓶-热力泵。阐述了该热力泵的设计要求及试验研究的方法。     

一种基于数据挖掘的入炉燃料发热量在线智能软诊断方法研究

国内许多火电站燃烧煤质波动对锅炉的稳定燃烧和安全运行构成了严重威胁,主要矛盾反映在燃料低位发热量太低,经常在炉内无法稳定燃烧。针对锅炉燃料发热量大范围波动工况下的燃烧数据特性,提出了关联信息算法和非线性映射网络的混合模型。利用此模型对国内某300 MW电站锅炉现场燃烧数据进行了计算和分析,得到了判断燃料发热量变化的诊断规则知识,可以较好地预测燃料发热量的变化,优化运行人员的操作。该方法实施性强,投入成本小,而且还可以无缝地集成至现有的SIS平台中,完善锅炉系统的实时性能诊断模块,提升SIS系统二次开发的空间。     

Performance study of a solid oxide fuel cell and gas turbine hybrid system designed for methane operating with non-designed fuels

This paper presents an analysis of the fuel flexibility of a methane-based solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system. The simulation models of the system are mathematically defined. Special attention is paid to the development of an SOFC thermodynamic model that allows for the calculation of radial temperature gradients. Based on the simulation model, the new design point of system for new fuels is defined first; the steady-state performance of the system fed by different fuels is then discussed. When the hybrid system operates with hydrogen, the net power output at the new design point will decrease to 70% of the methane, while the design net efficiency will decrease to 55%. Similar to hydrogen, the net output power of the ethanol-fueled system will decrease to 88% of the methane value due to the lower cooling effect of steam reforming. However, the net efficiency can remain at 61% at high level due to increased heat recuperation from exhaust gas. To increase the power output of the hybrid system operating with non-design fuels without changing the system configuration, three different measures are introduced and investigated in this paper. The introduced measures can increase the system net power output operating with hydrogen to 94% of the original value at the cost of a lower efficiency of 45%.     

A combined thermodynamic cycle used for waste heat recovery of internal combustion engine

In this paper, we present a steady-state experiment, energy balance and exergy analysis of exhaust gas in order to improve the recovery of the waste heat of an internal combustion engine (ICE). Considering the different characteristics of the waste heat of exhaust gas, cooling water, and lubricant, a combined thermodynamic cycle for waste heat recovery of ICE is proposed. This combined thermodynamic cycle consists of two cycles: the organic Rankine cycle (ORC), for recovering the waste heat of lubricant and high-temperature exhaust gas, and the Kalina cycle, for recovering the waste heat of low-temperature cooling water. Based on Peng–Robinson (PR) equation of state (EOS), the thermodynamic parameters in the high-temperature ORC were calculated and determined via an in-house computer program. Suitable working fluids used in high-temperature ORC are proposed and the performance of this combined thermodynamic cycle is analyzed. Compared with the traditional cycle configuration, more waste heat can be recovered by the combined cycle introduced in this paper.     

A general formula for the evaluation of thermodynamic and aerodynamic losses in nucleating steam flow

Near saturation steam undergoing rapid expansion, with homogeneous nucleation of water droplets, is numerically studied in a series of converging/diverging nozzles with and without shocks. To understand loss mechanisms in such flows a numerical model is presented to calculate thermodynamic losses, which is further used to quantify associated total aerodynamic losses. For the converging/diverging nozzle configuration, the model shows that the overall thermodynamic loss is only mildly influenced by increasing shock strength, while the aerodynamic losses follow that of the single phase flow, and are of the same magnitude as the thermodynamic loss only in the case of very weak shocks. The thermodynamic losses can be attributed to two influences, the homogeneous nucleation event, and the post-shock thermal oscillations in the two-phase system. The calculations rely on a new two-phase CFD model, previously reported, for non-equilibrium phase change with droplet nucleation applicable to general 3D flow configurations.     

Exergetic analysis of distillation processes—A case study

The concept of exergy has been introduced to establish a universal standard for quality and efficient use of energy. In this work, applications of this concept to compression, heat exchange, and separation processes, in addition to the computation of their irreversibility rate and thermodynamic efficiency, are considered. An industrial case study on the purification of 1,2-ethylenedichloride (EDC) in a high-purity distillation column is presented. Due to its large throughput, this distillation column consumes a large amount of thermal energy (steam to the reboiler) and in order to reduce the energy requirements without large process modifications, a new configuration using a vapour compression heat pump is proposed which yields considerable improvement in the use of energy. Both configurations were implemented using the commercial simulator Aspen Plus™; the results of the original configuration were validated with data extracted from the plant. The objective of this work was to compare the original configuration and the new proposed one, from a thermodynamic approach. Furthermore, two forms of process thermodynamic analysis based on the concept of exergy were applied to the new proposed configuration.     

The need for exergy analysis and thermodynamic optimization in aircraft development

This paper outlines a newly emerging body of work that relies on exergy analysis and thermodynamic optimization in the design of energy systems for modern aircraft. Exergy analysis establishes the theoretical performance limit. The minimization of exergy destruction brings the design as closely as permissible to the theoretical limit. The system architecture springs out of this constrained optimization principle. A key problem is the extraction of maximum exergy from a hot gaseous stream that is gradually cooled and eventually discharged into the ambient. The optimal configuration consists of a heat transfer surface with a temperature that decays exponentially in the flow direction. This configuration can be achieved in a counterflow heat exchanger with an optimal imbalance of flow capacity rates. The same optimal configuration emerges when the surface is minimized subject to specified exergy extraction rate. Similar opportunities for optimally matching components and streams exist in considerably more complex systems for power and refrigeration. They deserve to be pursued, and can be approached first at the conceptual level, based on exergy analysis and thermodynamic optimization. The application of such principles in aircraft energy system design also sheds light on the “constructal” design principle that generates all the systems that use powered flight, engineered and natural, cf. constructal theory.