A simulation study on the enhancement of the shift reaction by water injection into a gasifier

Although coal gasification is a clean and efficient use of coal, a reduction of CO₂ emissions is needed to mitigate global warming. The aim of this study was to improve the thermal efficiency of fuel production and electricity generation by dry coal feed gasification. The primary cause of thermal efficiency loss is steam use in a water-gas shift reactor. The shift reactor, installed downstream from the gasifier, uses a catalyst to adjust the H₂/CO ratio of the syngas. We have proposed a new process in which water is injected at the outlet of the gasifier and is vaporized to enhance the extent of the shift reaction. This process utilizes the high temperature of the syngas, which is sufficient for the shift reaction to occur without a catalyst. We have developed a model that incorporates the shift reaction velocity to evaluate our proposed process. In an optimized 5-stage water supply case, we found that the CO conversion reaches 9.9% at a water/syngas ratio of 0.14 mol/mol (water/CO = 0.25 mol/mol); the CO conversion needed for dimethyl ether production is 31%. This new process can improve the efficiency and reduce the cost of coal gasification.     

商业车辆变速器的因素——性能,换档平顺性,噪时状况

Ｅｃｏｓｐｌｉｔ３系列的样机现代化表示的重要特征是不改变原来整个设计原理而能大大改进变速器的转矩能力、档平顺性和噪音状况。斜齿行星齿轮装置可使变速 降低１０分贝、在车辆变速败露首次采用了“锥形止推垫圈”技术，可使该行呈齿轮传动中的斜齿轮的轴向力自身消除。     

Thermodynamic investigation of methanol and dimethyl ether synthesis from CO2 Hydrogenation

The thermodynamics involved in the catalytic hydrogenation of CO₂ have been examined extensively. By assuming that methanol and dimethyl ether (DME) are the main products, two reaction systems each consisting of two pararell reactions were analyzed and compared in terms of the equilibrium yield and selectivity of the useful products, methanol and DME. The calculation results demonstrated that the production of DME allows much higher oxygenate yield and selectivity than that of methanol.     

对气测全量曲线“负漂”的认识及资料应用价值的探讨

对于TDC—综合录井仪的气测全量曲线“负漂”成因机理,通过理论分析和现场试验,有了初步认识。全量曲线“负漂”峰是惠斯顿电桥鉴定器测量低导热系数气体的正常反应,它对判断CO_2气体和N_2气体的存在有较好的应用价值。它可为今后进一步研究地层中高矿化度水层、油水同层和气水同层的解释方法提供一项特殊价值的气测分析资料。     

高温局部荷载作用下短粗腹板的失效机制

提出计算高温和局部荷载作用下短粗热轧钢板的极限强度的分析模型。该局部荷载可能出现在火灾中钢框架结构梁柱连接的受压区,由集中荷载所产生。建模中假定翼缘上的理想塑性铰会导致腹板屈服,计算没有考虑板的局部屈曲。根据温度区域和连接受压区的长度提出两种可能的失效机制,这与周边温度升高时构件的失效屈服不同。基于本文提出的分析模型,对一个典型连接件进行参数研究,归纳不同的热梯度和局部荷载作用长度下腹板极限强度的变化。分析结果表明:在对钢结构进行防火设计时,必须考虑到连接件在高温下的反应,才能提高建模的准确性。     

基于SIMULINK/STATEFLOW的双离合自动变速器换档策略研究

根据双离合自动变速器(DCT)的特点,制定了DCT换挡规律及换挡控制策略,并通过MATLAB/Simulink/Stateflow平台建立模型进行分析验证。试验结果表明所制定的DCT换挡控制逻辑的正确性。     

Pressure measurements in steel silos with eccentric hoppers

It is known that concentric filling and discharge are the most recommended solutions in silo design. However, different reasons such as costs, space problems and the client's specific requirements have a significant influence on the final design. Therefore, engineers sometimes need to make use of eccentric filling and discharge solutions. These designs are usually related to phenomena such as unfavorable switches in the flow regime, associated with extreme unsymmetrical pressure distributions around the silo wall, oscillations of the load, etc., which may cause failures or instabilities of silo structures, involving then high costs for the industry and, in the worst cases, accidents where human life may be endangered. Understanding about these phenomena associated with hopper eccentricities is still needed.This research work deals with pressure measurements on three steel silos with different hopper eccentricities. The results not only confirm, at a qualitative level, phenomena that have also been described in previous research, but also provide new knowledge concerning non-symmetric loads in wheat and maize silos with conical hoppers of different eccentricities. Non-symmetric components of the pressures and shifts in flow regimes have been studied and discussed in relation to load assessment for the design of silos.     

一种微带反射阵列天线单元特性研究

带开路短截线的贴片是微带反射阵列天线设计中最常用的单元形式之一。结合应用于民用航天领域的薄膜反射阵列天线设计,比较和分析不同物理参数、阵列环境下单元电讯性能变化特点,并优化设计单层薄膜反射阵列天线试验阵面,给出分析结果,供不同应用背景下的反射阵列天线设计参考。     

基于左手介质的贴片天线技术研究

介绍和分析了左手介质的构造原理和方法,通过对加载左手介质材料的贴片天线的研究,来说明左手介质天线的一些优异特性。仿真和实测结果表明,通过加载左手介质材料,普通贴片天线会产生新的特性,如工作频率的降低、天线增益的提高、方向性的增强等。而且,天线的物理尺寸能得到很大的减小,这就为高增益、高带宽的小型化贴片天线设计提供了新的方法和思路。     

龙岩某冲孔灌注桩基础事故的处理与分析

本文以龙岩市商会大厦桩基工程施工为背景,通过对某桩基事故的处理与分析,介绍了冲孔灌注桩工艺在溶洞、裂隙发育地区施工过程中,由于地质情况复杂或者施工控制不当等情形下造成的问题所采用施工处理措施。