A comparative simulation study of power generation plants involving chemical looping combustion systems

This work presents a simulation study on both energy and economics of power generation plants with inherent CO₂ capture based on chemical looping combustion technologies. Combustion systems considered include a conventional chemical looping system and two extended three-reactor alternatives (exCLC and CLC3) for simultaneous hydrogen production. The power generation cycles include a combined cycle with steam injected gas turbines, a humid air turbine cycle and a simple steam cycle. Two oxygen carriers are considered in our study, iron and nickel. We further analyze the effect of the pressure reaction and the turbine inlet temperature on the plant efficiency. Results show that plant efficiencies as high as 54% are achieved by the chemical looping based systems with competitive costs. That value is well above the efficiency of 46% obtained by a conventional natural gas combined cycle system under the same conditions and simulation assumptions.     

谈常绿植物在园林中的应用

常绿植物对于园林绿化的效果有着很大的影响，可以有效提高园林绿化的质量，不仅美化环境，同时还可以保护生态环境，为人们的生活增添色彩。本文首先论述了常绿植物在园林中配置的原则，然后以辽阳市为例探讨了常绿植物在园林中的应用，供相关工作人员参考和借鉴。     

Coordinated operation of wind turbines and flywheel storage for primary frequency control support

This work assesses the participation of wind power plants in primary frequency control support. To participate in frequency control-related tasks, the wind power plants have to maintain a certain level of power reserves. In this article, the wind power plant is equipped with a flywheel-based storage system to fulfil the power reserve requirements set by the network operator. The article focuses on two main aspects: the definition of the control strategy to derate the wind turbines to provide a part of the required power reserves; and the coordinated regulation of the power reserves of the wind turbines and the flywheels while participating in primary frequency control. This coordinated regulation enables the wind power plant to maintain the net level of power reserves set by the network operator while alleviating the need of deloading the wind turbines. The performance of the proposed control schemes are shown by simulation.     

Use of symmetry theory in studying the morphogenesis of life forms: the example of the cushion plants

It is well known that life forms reflect the impact of the environment. An interesting task in ecology is to study the connection between the morphological characteristics of life forms and physical and geographical processes, taking place in the environment. This study may profit from the application of symmetry theory which is a universal methodology in science. According to this theory both the object, that is, life form, and the environment are characterised by their own types of symmetry, which may differ from each other. If the environment acts sufficiently intensively on a plant, its form may show deformations – dissymmetry according to Curie. From the observed dissymmetry character of the vegetation it is possible to judge the symmetry of the environment, its specific impact on the vegetation, and the direction and intensity of natural matter and energy flows. All these are clearly apparent in the cushion plants growing on the abrupt slopes of south‐east Altay canyons.     

Analysis of chemicals and energy consumption in water and wastewater treatment,as cost components: Case study of Oslo,Norway

Adopting a systems-approach to an urban water and wastewater system, while applying a triple bottom line strategy to management, entails a careful analysis of all the sub-systems and components thereof with a view to improving service levels, optimising expenditure, augmenting investments, and also reducing the life-cycle environmental impacts associated with setting up, maintaining and operating the system. The scope for optimising expenses is system-wide, though it varies from one sub-system to another, depending on inherent lock-ins and external factors beyond the direct control of the water and wastewater utility. Optimising the consumption of energy and chemicals and improving the cost-efficiency thereof, is always on the agenda of water treatment plants (WTPs) and wastewater treatment plants (WWTPs). This paper analyses the consumption of and the expenditure on chemicals and energy at Oslo's WTPs and WWTPs over time. Energy and chemicals for water and wastewater treatment, on an average account for 10.8% of the total operational expenses in the water supply sub-system and 13.7% for the wastewater handling sub-system. There is a perceptible increase in this share from 5.2% in 2004 to 14.9% in 2009 for water and 12.3% to 14.2% for wastewater. Chemicals cost more than energy for the WWTPs, while it was the other way round for the WTPs. The total real cost of energy and chemicals per cubic metre, in year-2007 currency, was between 4 and 5.2 Euro cents for the WTPs, and between 1 and 4.5 Euro cents for the WTPs. The total (WTP + WWTP) per-capita real costs of energy and chemicals, expressed in year-2007 currency, rose from around 10 Euros in year 2000 to about 12.2 Euros in year 2007.     

基于多线程运行控制的高效节能型净水工艺

华北地区某净水厂以当地水库水为水源,原水受到有机物污染,水质受季节影响变化较大。为应对上述水质问题采用高密度沉淀池—V型滤池—超滤—臭氧加活性炭吸附的工艺流程,但该工艺流程较长,运行能耗较高。针对季节和水质变化,以供水安全可靠为前提,高效节能为目标,提出了水厂运行的多线程工艺流程。经节能评估,运行改进后可节能23.96%。     

核电站不锈钢贮罐焊接变形控制

以核电站换料水箱为例,介绍了换料水箱功能、设计要求、换料水箱组成、制造流程;分析了00Cr19Ni10(304L)材料的焊接特点、焊接施工过程中的难点、焊接变形的原因;总结控制焊接变形的焊接原则、焊接变形控制方法和焊接变形控制措施。为核电站后续贮罐现场焊接变形控制提供依据。     

Numerical Investigation on Residual Stresses of the Safe-End/Nozzle Dissimilar Metal Welded Joint in CAP1400 Nuclear Power Plants

The residual stress evolution in a safe-end/nozzle dissimilar metal welded joint of CAP1400 nuclear power plants was investigated in the manufacturing process by finite element simulation. A finite element model, including cladding, buttering, post-weld heat treatment (PWHT) and dissimilar metal multi-pass welding, is developed based on SYSWELD software to investigate the evolution of residual stress in the aforementioned manufacturing process. The results reveal a large tensile axial residual stress, which exists at the weld zone on the inner surface, leads to a high sensitivity to stress corrosion cracking (SCC). PWHT process before dissimilar metal multi-pass welding process has a great influence on the magnitude and distribution of final axial residual stress. The risk of SCC on the inner surface of the pipe will increase if PWHT process is not taken into account. Therefore, such crucial thermal manufacturing process such as cladding, buttering and post-weld heat treatment, besides the multi-pass welding process, should be considered in the numerical model in order to accurately predict the distribution and the magnitude of the residual stress.     

基于改进型Smith预估器的同步施工网络控制系统

根据同步施工网络控制系统的控制原理,分析了时变、随机和不确定的网络时延对同步误差控制所产生的影响。针对传统Smith预估器用于多被控对象同步控制时存在的缺陷与不足进行了分析,提出了一种改进型Smith预估器,实现了对网络时延、被控对象纯滞后因子以及同步误差控制器的多重Smith预估补偿,将其从内部反馈回路中彻底消除,预估模型无需预估与在线测量其大小与变化规律。通过基于控制器局域网络(controller area network,简称CAN)的盾构管片拼装机同步网络控制系统,对常规比例积分微分(proportion integral derivative,简称PID)同步网络控制和基于改进型Smith预估器的PID同步网络控制性能进行了仿真对比分析,并通过实验进行了验证。结果表明,常规PID网络控制同步误差为-3～3mm,基于改进型Smith预估器的PID网络控制同步误差为-1.5～1.5mm,后者可显著提高同步施工网络控制系统的同步控制性能与精度。