Energy conserving effects of dividing wall column

The energy-conserving performance of dividing wall column(DWC) is discussed in this paper. The heat transfer through the dividing wall is considered and the results are compared with that of common heat insulation dividing wall column(HIDWC). Based on the thermodynamic analysis of heat transfer dividing wall column(HTDWC) and HIDWC, both computer simulation and experiments are employed to analyze the energyconserving situation. Mixtures of n-hexane, n-heptane and n-octane are chosen as the example for separation.The results show that the energy consumption of HTDWC is 50.3% less than that of conventional distillation column, while it is 46.4% less than that of HIDWC. It indicates that DWC is efficient on separating threecomponent mixtures and HTDWC can save more energy than HIDWC. Thus it is necessary to consider the heat transfer while applying DWC to industry.

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.

Numerical Investigation on Effect of Vapor Split Ratio to Performance and Operability for Dividing Wall Column

Operability problem of dividing wall column (DWC) raised by vapor split was investigated by numerically analyzing four cases defined by different compositions of a three-component mixture. DWCs were firstly designed for each case by optimizing the vapor split to the two sides of the dividing wall, and then their feasibilities and total annual costs in operation were evaluated against different vapor split ratios. The analysis on the operability of the DWC for four cases was made based on two scenarios: (1) vapor split is shifted by the vapor resistance difference between the column sections in the two sides of the dividing wall and (2) the feed composition is changed. It was demonstrated that the positioning of the dividing wall and the decision on the vapor split may affect significantly the operability of a DWC.

Reactive dividing wall column for hydrolysis of methyl acetate:Design and control

Reactive distillation and dividing wall column distillation are two kinds of effective separation technologies,and their integrated configuration,reactive dividing wall column(RDWC),presents attractive advantages.In this study,the rigorous simulation of RDWC for methyl acetate hydrolysis is performed,and sensitivity analysis is conducted to obtain the minimum reboiler duty.Then a comparison is made between the conventional process and RDWC process,and it shows that 20.1% energy savings can be achieved by RDWC process.In addition,the dynamic characteristic of RDWC is studied and an effective control strategy is proposed.The simple PI control scheme with three temperature loops can obtain reasonable control performance and maintain products at desired purities.It is proved that this RDWC process is an energy efficiency alternative with good controllability.

Composition control and temperature inferential control of dividing wall column based on model predictive control and PI strategies

The dividing wall column （DWC） is considered as a major breakthrough in distillation technology and has good prospect of industrialization. Model predictive control （MPC） is an advanced control strategy that has acquired extensive applications in various industries. In this study, MPC is applied to the process for separating ethanol, n-propanol, and n-butanol ternary mixture in a fully thermally coupled DWC. Both composition control and tem- perature inferent/al control are considered. The multiobjective genetic algor/thm function ＂gamult/obj＂ in Matlab is used for the weight tuning of MPC. Comparisons are made between the control performances of MPC and PI strategies. Simulation results show that although both MPC and PI schemes can stabilize the DWC in case of feed disturbances, MPC generally behaves better than the PI strategy for both composition control and tempera- ture inferential control, resulting in a more stable and superior performance with lower values of integral of squared error （ISE）.

Control of reactive dividing wall column for selective hydrogenation and separation of C3 stream

In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.

Application of the dividing wall column to olefin separation in fluidization methanol to propylene(FMTP) process

Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in the present work.Detailed design for pilot DWC was performed and five control structures,i.e.composition control(CC),temperature control(TC),composition-temperature control(CC-TC),temperature difference control(TDC),double temperature difference control(DTDC)were proposed to circumvent feed disturbance.Sensitivity analysis and singular value decomposition(SVD)were used as criterion to select the controlled temperature locations in TC,CC-TC,TDC and DTDC control loops.The steady simulation result demonstrates that 25.7% and 30.2% duty can be saved for condenser and reboiler by substituting conventional column sequence with DWC,respectively.As for control structure selection,TC and TDC perform better than other three control schemes with smaller maximum deviation and shorter settling time.

Investigation of the operability for four-product dividing wall column with two partition walls

For separating some specific four component mixtures into four products, the four-product dividing wall column(FPDWC) with two partition walls can provide the same utility consumption with the extended Petlyuk configuration, although with structure simplicity. However, the reluctance to implement this kind of four product dividing wall column industrially also consists in the two uncontrollable vapor splits associated with it. The vapor split ratios are set at the design stage and might not be the optimal value for changed feed composition, thus minimum energy consumption could not be ensured. In the present work, a sequential iterative optimization approach was initially employed to determine the parameters of cost-effective FPDWC. Then the effect of maintaining the vapor split ratios at their nominal value on the energy penalty was investigated for the FPDWC with two partition walls, in case of feed composition disturbance. The result shows that no more than + 2% above the optimal energy requirements could be ensured for 20% feed composition disturbances, which is encouraging for industrial implementation.

Shear reinforcement effect of reinforced concrete tie-columns on the lateral resistance of confined masonry walls

Tie-columns improve significantly the lateral resistance of masonry bearing walls against persistent, transient and accidental loads. The research work described herein has been carried out to assess the lateral resistance of confined masonry walls, where contribution of the masonry panel is evaluated according to material mechanics and tie-columns effect is estimated by a proposed analytical formulation based on a model reported on previously. This approach takes into account the effect of dowel support on the reaction of its adjacent shear reinforcement： the conditions for the various contributions of transverse reinforcements are better defined following a clear evaluation of the participation ratio of these reinforcements. Lateral resistances of confined masonry walls measured in full-scale tests and gleaned from the literature are compared and checked with resistances calculated using the present approach.

窄翼缘异形柱-波纹钢板剪力墙体系的抗震性能

针对钢结构住宅凸梁、凸柱和抗侧刚度不足的问题,提出一种新型窄翼缘异形柱-波纹钢板剪力墙体系;通过与传统H形钢柱-平钢板剪力墙体系进行对比,确定内嵌波纹钢板布置方式,采用ABAQUS软件建立所提出体系的有限元模型,对所提出体系的抗震性能进行分析,探讨外部框架截面形式与布置方式、波纹钢板厚度与剪跨比等对所提出体系的抗侧承载力、耗能能力和塑性变形能力的影响。结果表明:所提出的体系具有较大的抗侧承载力和较强的耗能能力、塑性变形能力,极限抗侧承载力为设计值的1.73倍,具备一定的安全储备;横向布置的波纹钢板能有效减小其作用于框架梁柱的荷载;采用十字形异形柱使所提出的体系有更强的塑性变形能力;所提出体系中的异形柱偏肢宜沿剪力墙面内方向布置,内嵌波纹钢板厚度宜取为3~5 mm,剪跨比宜控制在1.25左右。

湿壁塔实验台控制系统的研发

随着二氧化碳排放问题的日益严峻,加速二氧化碳的减排计划已经刻不容缓。其中,对于二氧化碳吸附剂的研究是减排的重中之重。为了准确高效地研究二氧化碳吸附剂的传质特性,开发一套湿壁塔实验台控制系统,通过PLC对湿壁塔实验台的温度、压力和流速等参数进行数据采集与精确控制。详细介绍实验装置的工作原理与实验流程,以及组态软件的参数设定、远程控制、实时监控和报警等功能。该系统能够简化实验流程,提高实验效率,为吸附剂的研究提供可靠的理论和实践基础。

Wing walls for enhancing the seismic performance of reinforced concrete frame structures

A building retrofitted with wing walls in the bottom story, which was damaged during the 2008 M8.0 Wenchuan earthquake in China, is introduced and a corresponding 1/4 scale wing wall-frame model was subjected to shake table motions to study the seismic behavior of this retrofitted structural system. The results show that wing walls can effectively protect columns from damage by moving areas that bear reciprocating tension and compression to the sections of the wing walls, thus achieving an extra measure of seismic fortification. A ‘strong column-weak beam＇ mechanism was realized, the flexural rigidity of the vertical member was strengthened, and a more uniform distribution of deformation among all the stories was measured. In addition, the joint between the wing walls and the beams suffered severe damage during the tests, due to an area of local stress concentration. A longer area of intensive stirrup is suggested in the end of the beams.

Experimental Study on Improving Seismic Behavior of Load-Bearing Masonry Wall Made of Autoclaved Aerated Concrete

To investigate the seismic behavior of autoclaved aerated concrete load-bearing masonry wall(AACLMW), a piece of control block wall without constructional measures and five pieces of block walls with different constructional measures were tested under low reversed cyclic loading which imitated low to moderate earthquake force. The seismic behavior of AACLMW with different constructional measures in terms of failure mode, hysteretic curve, deformation capacity and displacement ductility was studied and compared with that without constructional measures. The experimental results indicate that the constructional measures comprising constructional columns and horizontal concrete strips are effective for improving the seismic behavior of AACLMW. The study in this paper can provide a reliable experimental basis for further analysis and engineering application of AACLMW in the future.

基于自热再生的隔壁塔深冷空分工艺设计及优化

工业气体应用广泛,当前常用深冷精馏法获取,工艺能耗巨大,其中压缩和精馏部分的耗能占比最大。基于自热再生和隔壁塔技术,提出了一种隔壁塔深冷空分方案,用单塔精馏空分过程代替双塔精馏空分过程,利用自热再生优化过程换热。利用夹点原理对优化前后的工艺进行能量分析,并从总能量消耗(TEC)、二氧化碳排放量([CO_(2)]em)、年度总费用(TAC)三个角度分别进行评价。结果表明,基于自热再生的隔壁塔深冷空分工艺较常规空分工艺,制氧消耗降低了26.19%,二氧化碳排放减少了25.18%,年度总费用降低了31.93%。利用自热再生技术和隔壁塔技术优化后的空分工艺,在节能、经济以及环保方面表现出更强的优越性。

广州名盛广场结构新技术设计及应用

介绍了广州名盛广场采用的多项结构新技术的设计和应用特点,着重说明了采用带约束拉杆异形钢管混凝土柱(墙)的新型混合结构框架-剪力墙筒体结构体系及柱支式地下连续墙地下室逆作法的设计特点,并对工程中应用的45m跨度预应力钢-混凝土组合拱架结构等转换结构的设计及构造进行介绍。

初始缺陷对除尘器壳体立柱轴压稳定性的影响

为考虑除尘装备壳体加劲钢板墙板-H型钢立柱结构体系中初始缺陷的影响,采用非线性有限元方法,研究初始几何缺陷和焊接缺陷对立柱承受轴向压力时失稳模态和稳定承载力的影响。研究结果表明:较为不利的初始几何缺陷形态是立柱截面的初始弯扭变形,较为不利的发生最大初始几何变形的位置在靠近柱顶的高轴力区。焊接残余变形对壳体立柱轴压稳定性影响很小,焊接残余应力对壳体立柱稳定性有微小的有利影响。构建壳体立柱轴压稳定性数值计算模型时,可以引入施加定向干扰的完善结构极值点模态缺陷,以充分考虑初始几何缺陷影响;无需考虑焊接残余应力影响。

萃取精馏隔壁塔分离乙酸乙酯-乙腈共沸物系的模拟与优化

利用Aspen plus软件对乙酸乙酯-乙腈共沸物系采用萃取精馏方案进行模拟和全局经济优化。在此基础上,对该物系提出了萃取精馏隔壁塔三塔等价模型分离方案,并对该流程进行模拟和优化。结果表明:萃取精馏隔壁塔较传统萃取精馏塔在节约能耗和减少设备投资方面有明显的优势,萃取精馏隔壁塔方案比传统两塔萃取精馏方案在年度设备投资费用上节约22.1%,年度操作费上节约8.3%,年度总费用上节约13.1%。并且将塔底循环萃取剂与原料进行换热,进而进一步减少了能耗。这一研究将对工业分离乙酸乙酯-乙腈共沸混合物提供理论指导意义。

新型墙体轴压性能试验和数值分析

冷弯薄壁型钢住宅体系作为一种绿色建筑在我国已经开始得到应用,但相应的理论和试验研究极少。通过对这类住宅体系的墙体轴压性能进行试验研究和有限元分析,提出了构件稳定设计的有效计算长度系数,并与AISI规范(1996)计算结果进行了比较。研究表明墙体覆盖面板可以提高墙体骨架的承载力,相当于蒙皮效应。所做工作可为我国编制这类新型住宅的设计规范提供参考。

分离丙酮-乙醇-水物系的隔壁塔设计与优化

利用Aspen Plus模拟软件,建立了分离丙酮-乙醇-水物系的隔壁塔工艺流程。在保证丙酮产品纯度不低于99.2%的前提下,使用响应面法分析了隔壁塔的结构参数对能耗的影响,拟合出塔结构参数与再沸器热负荷的二次方程,对隔壁塔的结构参数进行了优化。优化结果为:预分离段、公共精馏段、公共提馏段和侧线采出段的理论塔板数分别为22,20,19,18;预分离段的进料位置为第16塔板,公共提馏段的再沸器热负荷为405.63 k W。验证结果显示,优化结果与模拟结果的相对误差为0.65%,说明流程模拟与响应面法相结合用于隔壁塔结构参数的优化可行。与传统工艺相比,隔壁塔分离工艺的设备费用降低26.86%、年度总费用降低41.10%。

2010年上海世博会中国馆国家馆结构体系

文中介绍了2010年上海世博会中国馆国家馆的总体概况———4个筒体从地区馆升起,空中连成整体作为展厅,层叠出挑,呈倒四棱台斗冠状.阐述了国家馆的一些结构设计特点———依建筑外形设置的斜柱,为楼盖大梁提供竖向支承,满足了展厅内没有柱子的大空间使用功能要求,通过加强斜柱根部楼层的连梁和楼盖刚度,使33.3 m标高楼盖自相平衡地受压而不是剪力墙受剪来承担更多的斜柱水平分力.此外,还介绍了41.4、49.5、60.3和69.9 m标高楼盖的结构布置及3根斜柱交汇处的节点做法、组合梁的起拱原则、内力较大处梁的做法、抗震设计等.