The operating cost of electrocoagulation

The electrocoagulation of kaolinite and bentonite suspensions was studied in a pilot electrocoagulation system at the Western Research Center of CANMET to assess the operating cost and efficiency of the process. Factors affecting the operating cost such as, the formation of passivation layers on electrode plates, flow velocity and concentration of sodium chloride in the suspension were examined. The operating costs investigated in this paper were the power cost of the electrocoagulation cell and the material cost due to the consumption of the aluminum electrode. Comparison was based on the settling properties of the treated product: turbidity, settling rate, and cake height. Higher concentration of sodium chloride resulted in greater amount of aluminum dissolved chemically and electrochemically into the suspension and thus a better clarity of the supernatant of the treated product. Increased flow velocity could reduce significantly the operating cost while improving both clarity of the supernatant and the compactness of the sludge volume. The passivation layers developed quickly with time during the electrocoagulation process and more energy became wasted on the layers.     

Selection of optimal operating conditions based on minimum energy consumption for an acrylonitrile recovery unit

The selection of the optimal operating conditions for an industrial acrylonitrile recovery unit was conducted by the systematic application of the response surface methodology, based on the minimum energy consumption and products specifications as process constraints. Unit models and plant simulation were validated against operating data and information. A sensitivity analysis was carried out in order to identify the set of parameters that strongly affect the trajectories of the system while keeping products specifications. The results suggest that energy savings of up to 10% are possible by systematically adjusting operating conditions.     

运行工况对双效空冷吸收式制冷循环性能的影响

采用空冷吸收器、空冷冷凝器实现循环空冷化,是缩小吸收式系统体积、扩大其应用领域的重要途径之一。针对4种空冷双效溴化锂循环,建立集中参数模型,分析比较了不同运行参数（热源温度、室外冷却空气温度、蒸发温度）对4种循环性能的影响情况。结果表明,要实现循环空冷化,必须提高热源温度,同时4种循环相比,溶液在低温溶液热交换器前分流的并联循环热力性能明显低于其他3种循环,不宜空冷化。     

Seawater desalination using PVDF-HFP membrane in DCMD process: assessment of operating condition by response surface method

Central composite design (CCD) was applied in this work to analyze the performance of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) flat sheet membrane in the seawater desalination using direct contact membrane distillation (DCMD) process. It is the most popular in response surface method (RSM). Development on Quadratic Regression model for membrane performance as a function of the operating conditions was studied. The ranges for each operating condition were selected as follows: feed temperature (T_f): 48–58?°C, feed flow rate (Q_f): 80–180?mL/min, permeate temperature (T_p):17–22?°C and permeate flow rate (Q_p): 80–180?mL/min. The model R-squared of 0.9759 (adjusted to degree-of-freedom), Lack-of-fit test (p?=?0.4764), predicted residual error sum of squared (PRESS) statistic of 10.3 suggest that the model is adequate to correlate the impact of operating conditions on permeates. ANOVA analysis showed that factors as feed flow rate, feed temperature, and permeate temperature have a valuable impact (p?≤?0.05) on the response variable. Additionally, the interaction among feed temperature-feed flow rate, feed flow rate-permeate flow rate, and the quadratic impact of feed temperature, permeate temperature, and permeate flow rate have shown an important impact (p?≤?0.05) on the permeate flux. Optimization of operating conditions to make the permeate flux and salt rejection high as possible was determined according to desirability function approach. A desirability of 0.969 was achieved at a feed temperature of 58?°C, feed flow rate of 180?mL/min, permeate temperature of 18.8?°C, and permeate flow rate of 145.3?mL/min in which a permeate flux of 12.56?kg/m²h and a salt rejection of 99.97% was obtained.     

有机朗肯循环发电系统变工况运行的实验研究

受余热热源及环境温度不稳定特性的制约,有机朗肯循环（ORC）发电系统在实际应用中需要有较强的变工况能力。本文以R245fa为工质,实验研究了在不同冷热源温度时,ORC系统在相同负载容量及膨胀机转速下的变工况运行特性及各部件实际性能。实验结果表明：热源温度主要决定了膨胀机的入口温度及过热度。随着热源温度的降低,膨胀机内部泄漏量变大,其等熵效率变低,单位质量工质做功能力变差,维持膨胀机做功状态的工质质量流量增加。由于工质在蒸发器内整体吸热量变小,系统发电效率随热源温度的降低而升高。在10℃冷源温度下,热源温度从115℃下降至100℃,机组的最大发电效率从5.03%升高至5.25%。改变冷源温度,主要作用于膨胀机的进出口压力,改变了膨胀机的做功状态。降低冷源温度,膨胀机压比升高,单位质量工质做功能力变强,维持膨胀机做功状态的工质质量流量减小。但由于膨胀机过膨胀运行带来的不可逆损失增加,膨胀机的等熵效率随冷源温度降低而减小。在115℃热源温度下,冷源温度从30℃下降至10℃,系统最大发电效率从6.08%升高至7.01%。     

催化裂化装置气压机喘振控制的双时间尺度动态模拟

压缩机工作时,当负荷降低到一定程度时,会产生剧烈的喘振现象。喘振会严重损坏机体,产生严重后果。旨在模拟催化裂化富气压缩机喘振及其控制,由于喘振产生的时间很短,与催化裂化运行时间相差数千倍,所以要在两个不同尺度时间下进行模拟。本文基于压缩系统机理模型在UniSim中开发了一个适用于压缩机主动控制的模型,同时为克服主动执行机构在压缩机稳定区带来的附加损耗,针对压缩机喘振现象设计了切换控制方案,在压缩机喘振时采用主动控制进行喘振控制,而在稳定工况点则取消主动控制作用。最后将该方案应用于压缩机双时间尺度模拟中,并从不同的时间尺度下对比了喘振控制对催化裂化过程的影响,整个过程验证了方案的有效性以及该方案可以同时解决防喘振控制使压缩机无法在高性能区工作和主动执行机构所带来的能耗增加的问题。     

GAMS supported optimization and predictability study of a multi-objective adsorption process with conflicting regions of optimal operating conditions

In process systems engineering, it is critical to design an effective and optimized process in a short period with minimum experimental trials. However, improvement of some process variables may deteriorate some other criteria due to conflicting regions of factor interests for optimal solution in multi-objective optimization (MOO) processes. Here, the global optimization of an adsorption case study with conflicting optimal solutions based on multi-objective Response Surface Methodology (RSM) design is facilitated with the implementation of BARON solver based on General Algebraic Modeling System (GAMS) with identical factor variables, levels, and model equations. RSM suggested fifteen different optimum settings of which the validation is quite expensive and onerous, whereas GAMS suggested a single optimum setting which makes it more economically viable especially for large scale systems. In addition, the GAMS-based optimization provided more accurate and reliable results when experimentally validated as compared to the RSM-based solution.     

Role of operating conditions in determining droplet size and viscosity of tackifier emulsions formed via phase inversion

Water‐based pressure‐sensitive adhesives are formulated by combining a polymer latex with a tackifier emulsion. The latter is an oil‐in‐water emulsion made by the process of phase inversion. The phase inversion itself is carried out in a stirred tank fitted with a heating jacket by progressively adding water to a water‐in‐oil emulsion. The point of onset of phase inversion and the characteristics of the emulsion that is formed depend on process conditions; these include temperature, rate of water addition, and agitation speed. The role of these operating conditions is elucidated here. Increasing temperature delayed the onset of phase inversion slightly, but it did not affect emulsion particle size, provided it remained below a critical value. Agitation speed had to be increased upon increasing the water flow rate to prevent increasing the particle size. Finally, the point of onset of phase inversion could be predicted reasonably well using a model available in the literature. © 2010 American Institute of Chemical Engineers AIChE J, 57: 96–106, 2011     

催化裂化装置吸收稳定系统的技术改造与操作优化

对中原油田分公司石油化工总厂Ⅱ套同轴式催化裂化装置进行了多次技术改造,通过改造吸收-稳定系统四塔内部构件,采取提高吸收塔压力、提高解吸塔热进料温度、控制稳定塔合适的回流比等措施,使干气中C_3~ 含量降到3％(体积)以下,液化气、稳定汽油产品合格率达100％。     

Zinc (II) ion recovery by biosorption onto powdered waste sludge (PWS): effects of operating conditions

Powdered waste sludge (PWS) obtained from a paint industry wastewater treatment plant and pretreated with 1% H₂O₂ was used for biosorption of Zn(II) ions from aqueous solution. The effects of operating conditions, pH, temperature, agitation speed, PWS particle size, Zn ion and PWS concentrations on the extent of Zn ion biosorption were investigated in batch experiments. The optimum pH resulting in maximum Zn ion biosorption was found to be pH = 5, since Zn ions precipitated in the form of Zn(OH)₂ at pH levels above 5. The rate and extent of Zn ion biosorption increased with temperature between 25 and 50 °C, although biosorption was not strongly sensitive to temperature variations since the activation energy was low at 4.5 kcal mol^?1. Biosorbent particle size had a significant effect on Zn ion biosorption, yielding high percentage Zn removals at small particle sizes (D_p < 100 µm) or large surface areas of PWS. Agitation speed also considerably affected the extent of Zn ion removal, and should be above 150 rpm in order to obtain a high rate. The extent of Zn ion biosorption was also affected by the initial Zn ion and PWS concentrations. At constant biosorbent (PWS) concentration, percentage Zn ion removal decreased, but the biosorbed Zn concentration increased with increasing initial Zn ion concentrations. However, at constant initial Zn concentrations, percentage Zn removal increased, but the biosorbed Zn ion concentration decreased with increasing adsorbent (PWS) concentration. With a maximum Zn ion biosorption capacity of 168 mg g^?1 powdered waste sludge was proven to be an effective biosorbent compared to other biosorbents. Copyright © 2006 Society of Chemical Industry     

工质泵变运行工况对有机朗肯循环系统性能的影响

有机朗肯循环（organic Rankine cycle, ORC）系统凭借其优越的性能已被应用于众多领域。工质泵是为ORC系统提供所需压力和流量的主要部件，其性能直接影响了其他部件性能及系统整体性能。本文通过理论计算分析了不同热力参数对单位质量流量工质泵输入功率及泵功指数的影响情况。进而以R245fa作为工质在冷凝温度为303K的模拟ORC系统工作条件下展开实验研究，分析变运行工况下两种不同类型工质泵（多级离心泵、液压隔膜计量泵）的运行参数变化规律及相互影响因素。进而探究工质泵变运行参数对ORC系统性能的影响。实验结果表明：液压隔膜计量泵的流量较低且受出口压力的影响较小，其输入功率最高仅为360.34 W，相同工况下仅是多级离心泵输入功率的16.29%。两者的实际运行效率随运行工况的变化而改变，最高分别可达59.96%、55.26%。结合理论计算，使用这两个泵的ORC系统泵功指数均在0.03～0.48范围内变化，热效率最高分别可达11.66%、10.35%。液压隔膜计量泵更适合于所需流量较低的ORC系统。     

四-[3-(3,5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯生产中酯交换反应工艺条件的优化

对由3,5-二叔丁基-4羟基苯丙酸甲酯(简称3,5-甲酯)与季戊四醇进行酯交换反应合成四-[3-(3,5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯(简称抗氧剂1010)的工艺条件进行了研究,分析了催化剂加入量、反应物配比、反应温度及反应时间等因素对酯交换反应的影响,优化了工艺条件。结果表明,新工艺条件下生产的抗氧剂1010产品质量为优级品。     

抗氧剂1010生产中加成反应工艺条件的优化

对由 2 ,6 -二叔丁基苯酚和丙烯酸甲酯进行加成反应合成 3,5甲酯的工艺条件进行了研究 ,分析讨论了反应物配比、加料方式、反应温度及反应时间等因素对加成反应的影响 ,优化了工艺条件。结果表明 ,新工艺条件下生产的 3,5 -二叔丁基 - 4羟基苯丙酸甲酯产品质量为优级品     

Effect of operating conditions in removal of arsenic from water by nanofiltration membrane

The removal of arsenic from synthetic waters and surface water by nanofiltration (NF) membrane was investigated. In synthetic solutions, arsenic rejection experiments included variation of arsenic retentate concentration, transmembrane pressure, crossflow velocity and temperature. Arsenic rejection increased with arsenic retentate concentration. Arsenic was removed 93-99% from synthetic feed waters containing between 100 and 382 μg/L as V, resulting in permeate arsenic concentrations of about 5 μg/L. Under studied conditions, arsenic rejection was independent of transmembrane pressure, crossflow velocity and temperature. In surface water, the mean rejection of As V was 95% while the rejection of sulfate was 97%. The co-occurrence of dissolved inorganics does not significantly influence arsenic rejection. The mean concentration of As in collected permeated was 8 μg/L. The mean rejection of TDS, total hardness and conductivity were 75, 88 and 75% respectively.     

An optimization study on the pyrolysis of polystyrene in a batch reactor

The pyrolysis process of polystyrene (PS) has been investigated to find optimal temperature profiles which minimize the reaction time and the reaction energy required for a given conversion in a batch reactor. Assuming that the fragmentation of PS in pyrolysis is described by the mechanism of random and/or specific degradations, we used a continuous kinetic model for solving three moment equations to determine the transient change of molecular weight distributions (MWD) of the polymers. We then converted this independent-variable minimization problem using a coordinate transformation to a dependent-variable minimization problem that yields the optimal temperature profiles as its solution. The optimization results obtained in this study encompass the cases of different objective functions which cover minimum reaction time, minimum energy consumed, or any combination of these. It has turned out that maintaining the reaction temperature constant at an optimal level is the best solution in this optimization problem. An economic cost function also has been introduced as the third objective function to be minimized in addition to the reaction time and the reaction energy. This new function can serve as a convenient measure to judge the performance of the pyrolysis process minimizing the involved cost.     

还原-偶氮光度法测定水中硝基苯优化测定条件研究

对还原-偶氮分光光度法测定水中硝基苯类实验装置进行改革,研究并建立了分析测定的优化实验条件。在此实验条件的基础上,对测定方法中的显色酸度、样品空白等测定条件进行了优化和补充;增加了苯胺类样品空白实验,解决了苯胺类样品及空白样品与体系酸度调节条件不一致的问题;同时拓宽了校准曲线的测定范围。硝基苯质量浓度在0~1.6 mg/L范围内线性关系良好,方法检出限为0.004 mg/L。用优化改进后的测定方法对水质硝基苯标准样品和实际废水样品进行分析测定,样品测定精密度(n=6)小于3%;加标实验回收率达到96.4%~101.8%。     

废水中氰化物加压水解反应动力学及工艺条件的优化

研究了含氰废水的加压水解反应动力学及反应条件。结果表明,KCN的加压水解反应对CN-符合一级反应动力学规律;在不同pH和水解温度下,KCN溶液中CN-加压水解反应速率常数不同;该水解反应平均活化能为33.2kJ/mol。实验证明,升高温度、增加溶液pH均可提高CN-的去除率;当pH>12时,CN-的去除率随pH变化趋缓。通过正交试验得出含氰废水加压水解的最佳处理条件为处理时间80min、温度180℃、pH为11.0,该条件下,对CN-质量浓度达300mg/L的含氰废水进行处理,CN-的去除率达91%以上。     

Influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors

Slurry reactors are popular in many industrial processes, involved with numerous chemical and biological mixtures, solid particles with different concentrations and properties, and a wide range of operating conditions. These factors can significantly affect the hydrodynamic in the slurry reactors, having remarkable effects on the design, scale-up, and operation of the slurry reactors. This article reviews the influences of fluid physical properties, solid particles, and operating conditions on the hydrodynamics in slurry reactors. Firstly, the influence of fluid properties, including the density and viscosity of the individual liquid and gas phases and the interfacial tension, has been reviewed. Secondly, the solid particle properties (i.e., concentration, density, size, wettability, and shape) on the hydrodynamics have been discussed in detail, and some vital but often ignored features, especially the influences of particle wettability and shape, as well as the variation of surface tension because of solid concentration alteration, are highlighted in this work. Thirdly, the variations of physical properties of fluids, hydrodynamics, and bubble behavior resulted from the temperature and pressure variations are also summarized, and the indirect influences of pressure on viscosity and surface tension are addressed systematically. Finally, conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.     

麦秸刨花板用PMDI胶粘剂固化条件的研究

以麦秸为原料、PMDI为胶粘剂,利用K型热电偶、自动平衡记录仪跟踪检测板材热 压过程中板材中心温度随热压时间的变化情况,初步对PMDI胶粘剂的固化适宜条件加以研 究,以指导生产实践,提高生产效率。