隔壁塔分离低碳混合醇动态控制研究

CO加氢制低碳混合醇是非石油基含碳资源再利用的重要途径之一,降低后续的分离能耗成为其工业化亟待解决的问题。文中在Aspen Dynamics平台上模拟了隔壁塔分离甲醇、乙醇、正丙醇、正丁醇的动态控制特性。在充分考虑液相分配量控制初馏塔塔顶压力的情况下,分析比较了LQ_R/DSB、DB/LSQ_R、DQ_R/LSB、LB/DSQ_R 4种动态控制策略。结果显示DB/LSQ_R在面对流量干扰时具有最好的控制性能。在此基础上进一步考察温度-组成的串级控制策略,结果表明,与纯组分控制相比,调节时间t和最大质量偏差A均明显减小,控制效果更佳。     

PTA装置醋酸脱水塔的动态模拟及控制策略分析

以PTA装置醋酸脱水塔为研究对象,在该醋酸脱水塔的稳态模型的基础上,通过建立的平衡级动态数学模型以及补充设置好的动态参数,利用Aspen Plus软件建立好动态模型。以Aspen Dynamics软件为工具,用回流流量控制灵敏板温度,塔釜再沸器热负荷与进料流量F ₁呈比例控制,模拟设计出了控制策略CS1。又为了保证在进料流量扰动时塔底醋酸浓度更加稳定,利用塔釜再沸器热负荷来控制塔釜醋酸浓度,设计出了控制策略CS2。将两种不同的控制策略对其动态响应进行分析比较,得出在相同目标条件下表现更优的控制策略,为实际生产和控制方案的设计提供方向和指导。     

隔壁塔萃取精馏制取无水异丙醇的模拟研究

提出一种隔壁塔萃取精馏制取无水异丙醇的新工艺．利用Aspen Plus模拟软件,对隔壁塔和常规萃取精馏工艺进行了模拟。确定了隔壁塔的主要参数：主塔为30块理论板,回流比为3．侧线精馏段为10块理论板,回流比为2,垂直隔壁位于塔内18块板到28块板之间。在此参数下．可得到质量分数99．92％的无水异丙醇;比较了2种流程的液相组成、温度及汽液相流量的变化。模拟结果表明：隔壁塔萃取精馏新工艺可以节省再沸器能耗15．6％．冷凝器能耗15.4％,能有效降低运行费用。     

跨壁传热隔壁塔的建模与实验研究

建立了存在隔板两侧传热的隔壁塔数学模型和小试实验装置,对比了灵敏板温度、能耗的模拟值和实验值。分析表明,气相分配比是影响模型准确度的主要参数,气相分配比与隔板两侧传热量有关,在原模型的基础上,修正气相分配比并联合拟合方程进行计算,模拟值与实验值吻合良好,修正后的跨壁传热隔壁塔模型准确合理,可应用于隔壁塔的数值模拟研究。     

石脑油分离隔壁塔综合性能模拟研究

在流程模拟软件Aspen Plus中建立石脑油分离隔壁塔模拟流程,利用传统石脑油分离两塔流程工艺参数作为初值,使用单因素变量法对隔壁塔工艺参数进行调整和优化。研究隔壁塔内主要操作和结构参数,如隔板位置、气液分配比、公共精馏段塔板数和提馏段塔板数对于隔壁塔能耗的影响。同时,研究了进料组成变化对于隔壁塔性能的影响。     

隔壁共沸精馏塔分离异丙醇水溶液的模拟

提出一种单塔共沸精馏生产无水异丙醇的新工艺流程,即采用隔壁塔替代常规共沸精馏流程中的脱水塔及提浓塔。应用Aspen Plus模拟软件,对隔壁共沸精馏塔流程及常规共沸精馏流程进行了模拟,比较了两种流程的液相组成、温度、汽液相流量及能耗,结果显示新工艺流程可以节省能耗14.6%,并能降低设备投资费用和操作费用。其模拟结果还需试验进一步验证。     

PTA装置醋酸脱水塔的动态模拟及控制策略分析

以PTA装置醋酸脱水塔为研究对象,在该醋酸脱水塔的稳态模型的基础上,通过建立的平衡级动态数学模型以及补充设置好的动态参数,利用Aspen Plus软件建立好动态模型。以Aspen Dynamics软件为工具,用回流流量控制灵敏板温度,塔釜再沸器热负荷与进料流量F1呈比例控制,模拟设计出了控制策略CS1。又为了保证在进料流量扰动时塔底醋酸浓度更加稳定,利用塔釜再沸器热负荷来控制塔釜醋酸浓度,设计出了控制策略CS2。将两种不同的控制策略对其动态响应进行分析比较,得出在相同目标条件下表现更优的控制策略,为实际生产和控制方案的设计提供方向和指导。     

垂直双隔板隔壁塔分离四组分的模拟优化和实验研究

提出了一种垂直双隔板的分离四组分混合物的隔壁塔,对该塔的结构设计进行了详细的介绍和说明,根据新型隔壁塔的塔板结构和分离原理设计了该种塔板的五塔模型并进行了简洁计算。针对烃类体系四组分分离的完全热耦合过程,通过化工流程模拟软件Aspen进行了模拟优化和用能分析,相比一般的序列塔分离工艺,节能最高可达18.6%,节能效果明显。根据工艺模拟结果,以分离戊烷、己烷、庚烷、辛烷为研究对象,对新型塔板进行了小试研究。研究结果表明：影响新型隔壁塔温度分布的主要因素是液相分配比,可通过控制新型隔壁塔主塔段二塔顶冷凝器的回流量来控制主塔段二的温度分布。研究为隔壁塔气相分配的工业化提供了理论依据和设计参考。     

垂直双隔板隔壁塔分离四组分的模拟优化和实验研究

提出了一种垂直双隔板的分离四组分混合物的隔壁塔,对该塔的结构设计进行了详细的介绍和说明,根据新型隔壁塔的塔板结构和分离原理设计了该种塔板的五塔模型并进行了简洁计算。针对烃类体系四组分分离的完全热耦合过程,通过化工流程模拟软件Aspen进行了模拟优化和用能分析,相比一般的序列塔分离工艺,节能最高可达18.6%,节能效果明显。根据工艺模拟结果,以分离戊烷、己烷、庚烷、辛烷为研究对象,对新型塔板进行了小试研究。研究结果表明:影响新型隔壁塔温度分布的主要因素是液相分配比,可通过控制新型隔壁塔主塔段二塔顶冷凝器的回流量来控制主塔段二的温度分布。研究为隔壁塔气相分配的工业化提供了理论依据和设计参考。     

反应精馏隔壁塔内合成乙酸甲酯的模拟

提出了一种应用反应精馏隔壁塔合成乙酸甲酯的新工艺流程,采用反应精馏隔壁塔替代常规反应精馏流程中的反应精馏塔及甲醇回收塔。利用Aspen Plus模拟软件,对反应精馏隔壁塔及常规流程进行了模拟,比较分析了两种流程塔内液相组成分布,并分析了塔顶回流比与气相分配比对反应精馏隔壁塔的影响。结果显示新流程可以节能11.9%,并能降低设备投资费用和操作费用。     

Male-specific conversion of the host plant compound,myrcene, to the pheromone, (+)-ipsdienol,in the bark beetle,Dendroctonus brevicomis

When both sexes of the bark beetle,Dendroctonus brevicomis LeConte, were exposed to vapors of myrcene from ponderosa pine, only the male produced (+)-ipsdienol. In the field, racemic ipsdienol significantly reduced the attraction of both sexes in flight to a mixture of myrcene and the aggregation pheromones,exo-brevicomin and frontalin. This suggests that ipsdienol may be involved in regulating colonization density ofD. brevicomis. The implications of the biosynthesis of various enantiomers of ipsdienol byD. brevicomis and the cohabitating bark beetles,Ips paraconfusus andI. pini, in relation to their behavioral responses are discussed in regard to reducing interspecific competition.Coleoptera: Scolytidae.     

电镀污泥中铜、镍、铬、锌的回收利用研究

研究电镀污泥中铜、镍、铬、锌的回收工艺流程,确定最佳的工艺条件。结果表明,电镀污泥中铜、镍、铬、锌的浸出率分别达到97.8%、98.6%、94.8%和99.0%,并可循环回收;废渣无害化,可按一般工业固废处置;生产过程闭路循环,无任何排放,实现清洁生产.     

Identification, Synthesis, and Field Testing of the Sex Pheromone of the Citrus Leafminer, Phyllocnistis citrella

The citrus leafminer is an important vector of citrus canker in many of the major citrus production areas of the world. (7Z,11Z)-Hexadecadienal was reported as a sex attractant for this insect in the 1980s, based on trap catches during pheromone screening trials in Japan. However, attempts to reproduce this work in other areas of the world have not been successful. We report here that (7Z,11Z)-hexadecadienal is only one component of the pheromone, with the other critical component being the analogous trienal, (7Z,11Z,13E)-hexadecatrienal. Both compounds were identified in the effluvia from live female moths by coupled gas chromatography (GC)-electroantennography using nonpolar and polar GC columns, and the identifications were confirmed by comparisons of mass spectra with those of authentic standards. Stereoisomers of the two compounds, and a number of analogs, were synthesized to confirm the identifications. In field trials, neither compound alone was attractive to male moths, but blends of the two were highly attractive, with thousands of insects being caught per trial. Addition of the isomeric (7Z,11Z,13Z)-hexadecatrienal inhibited attraction to the two-component blend. Electronic Supplementary Material Supplementary material is available for this article at and accessible for authorized users. This paper and the preceding paper (Leal et al.) were submitted within a few days of each other. The editors and the authors agreed that they should be published in tandem.     

Isolation,identification, synthesis,and bioassay of the pheromone of the comstock mealybug and some analogs

The sex pheromone of the Comstock mealybug,Pseudococcus comstocki (Kuwana) was isolated from volatiles trapped from air passing over virgin female insects. Combined gas chromatography, mass and infrared spectroscopy, and microreactions indicated that the structure was 2,6-dimethyl-1,5-heptadien-3-ol acetate. This was confirmed by synthesis; several analogs were also prepared. The natural and synthetic pheromone caused similar trap capture of male insects. Synthetic analogs were significantly less attractive in field tests and the addition of minor amounts of the corresponding alcohol to the pheromone appeared to enhance trap capture, but the results were not statistically conclusive.     

Fate of the Dietary Terpene, P-Cymene, in the Male Koala

The fate of the dietary terpene, p-cymene, is reported in a specialist Eucalyptus leaf folivore, the koala (Phascolarctos cinereus). Six male koalas were given two single oral doses of p-cymene (0.37 mmol/kg and 1.49 mmol/kg). Urine and feces were collected for two 24-hr periods after each dose and analyzed for metabolites by extraction, gas chromatography, and mass spectrometry. A total of six metabolites were detected in the urine. A novel, extensively oxidized metabolite, 4-(1,2-dihydroxy-1-methylethyl)-benzoic acid, was identified and its structure elucidated by high resolution and chemical ionization mass spectrometry. Minor amounts of two glycine conjugated metabolites were also detected. Five metabolites were present in sufficient amounts to quantify, using isolated urinary metabolites as reference standards. The mean fractional recovery of administered p-cymene was 0.77 ± 0.09 and 0.84 ± 0.12 for the low and high dose, respectively. The major metabolite excreted was the novel carboxy diol compound. No fecal metabolites were found. Thus, the koala employs a strategy in the metabolism of p-cymene that promotes the production of extensively oxidized metabolites that consequently have increased polarity and enhanced renal excretion. This strategy is compared with that employed by other Eucalyptus leaf folivores.     

热成型工艺的解决方案

成功的塑料热成型工艺解决方案,要求对加工工艺、模具设计、材料性能等因素进行全面综合分析。众多的热成型加工厂商往往只着眼于调整和改进工艺,以此来解决生产过程中所遇到的各种制品缺陷问题。其中采取的措施包括:试图延长加工循环周期、二次加工工序、或者通过改良设备装置     

Effect of concentration, temperature, moisture, liming and organic matter on the efficacy of the nitrification inhibitors benzotriazole, o-nitrophenol, m-nitroaniline and dicyandiamide

Laboratory experiments were carried out to study the effect of various factors that affect the efficacy of the nitrification inhibitors, benzotriazole, o-nitrophenol, m-nitroaniline and dicyandiamide. In a Paleustalf, increasing concentrations of the inhibitors from 0 to 15 mg/kg soil prolonged the nitrification up to 60 days. Increase in temperature from 10 to 30°C decreased the efficacy of all four nitrification inhibitors (by 6–62% at 30 days). Benzotriazole was equally effective in soil moisture conditions ranging from 40 to 80% of the maximum water holding capacity of the soil (WHC). o-Nitrophenol and m-nitroaniline were more effective at 60% WHC, while the efficacy of DCD was more at 40% WHC. Addition of 1000 mg/kg soil of fresh organic matter reduced the efficacies of o-nitrophenol, m-nitroaniline and benzotriazole by 55, 65 and 22%, respectively while the reduction in the efficacy of dicyandiamide was non-significant. Liming an acidic soil (Kandiustalf) to change the pH from 5.4 to 8.3 decreased the efficacies of the nitrification inhibitors and decreased the ammonium content in the soil at 30 days from 55 to 9 mg/kg in case of o-nitrophenol and m-nitroaniline and from 53 to 35 mg/kg in case of benzotriazole and dicyandiamide.     

Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene

From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom; (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation; (iii) the thermal softening of the phonons originates from bond expansion and weakening; and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.     

Impacts of Cys392, Asp393, and ATP on the FAD Binding,Photoreduction, and the Stability of the Radical State of Chlamydomonas reinhardtii Cryptochrome

Plant cryptochromes (CRYs) are blue-light receptors that regulate light-dependent growth, development, and circadian rhythms. A flavin adenine dinucleotide (FAD) cofactor is bound to the photolyase homology region (PHR) of plant CRYs and can be photoreduced to a neutral radical state under blue light. This photoreaction can trigger subsequent signal transduction. Plant CRYs can also bind an ATP molecule adjacent to FAD in a pocket of the PHR. Chlamydomonas reinhardtii contains a single plant CRY, named Chlamydomonas photolyase homologue 1 (CPH1). In CPH1, Cys392 and Asp393 are located near the FAD cofactor. Here we have shown that replacing Cys392 with Ser has little effect on the properties of CPH1. The C392N mutant, however, showed a faster photoreduction rate than wild-type CPH1, together with a significantly lower oxidation rate of the neutral radical state. Substituting an Asn residue for Asp393 in CPH1 improved the binding affinity for FAD as well as the stability of the neutral radical, but photoreduction in the case of this mutant was severely inhibited. In the presence of ATP, CPH1 and its mutants exhibited significantly higher binding affinity for FAD and slower oxidation of the neutral radical. These results reveal that the residues at site 392 and the presence of ATP can tune the stability of the neutral radical, that the Asp residue at site 393 is crucial for photoreduction, and that the photoreduction rate is not determined merely by the stability of the neutral radical in CPH1.