STEAM PRESSURE FILTRATION: MECHANICAL-THERMAL DEWATERING PROCESS

Abstract

Grain drying is a typical heat and mass transfer process with characteristics of multivariables, long time delay and nonlinearity. Thermodynamic modeling and control have been a subject of extensive research. Fuzzy logic provides a means for converting a linguistic control strategy, based on expert knowledge, into an automatic control strategy and is suitable for such process. In this article, the thermal characteristics of the grain drying process and the key factors influencing the final moisture content of the dryer are analyzed. On the basis of the analysis, an on-line measurement and fuzzy control scheme of the grain dryer are proposed. Finally, an on-line measurement and intelligent control software is developed and put into industrial application in a grain dryer. The practical control results show that the on-line measurement and intelligent control system of the dryer product satisfying control performance.     

Solvent Extraction of Heavy Lanthanides(III) with 5,7‐Dibromo‐8‐hydroxyquinoline from Aqueous Perchlorate Solution

Abstract

The extraction of Tb(III), Dy(III), Ho(III), Er(III), Tm(III), and Yb(III) with 5,7‐dibromo‐8‐hydroxyquinoline (Hdbq or HA) in chloroform from aqueous perchlorate solutions was investigated. The formation of the LnA₃ species (where Ln = Tb, Dy, Ho, Er, Tm, and Yb) in the organic phase was supported by the data. The parameters of the extraction processes were determined, and the separation factors between two adjacent lanthanides(III) were calculated.     

Solvent Extraction of Lanthanides(III) with N‐Cinnamoyl‐N‐phenylhydroxylamine and Its Trifluoromethyl Derivative

Abstract

N‐m‐Trifluoromethylcinnamoyl‐N‐phenylhydroxylamine (CF₃‐CPHA) was synthesized. The acid‐dissociation constant and distribution constant between chloroform and water of CF₃‐CPHA and N‐cinnamoyl‐N‐phenylhydroxylamine (CPHA), which was the mother compound of CF₃‐CPHA, were determined spectrophotometrically. The extraction behavior of tervalent lanthanides (Ln), Pr, Eu, and Yb into chloroform solution containing CPHA or CF₃‐CPHA was studied. They are extracted as self‐adduct chelates, LnL₃(HL)₃, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constants and separation factors for the lanthanides with CPHA and CF₃‐CPHA were evaluated. The extraction constant with CPHA are smaller than that obtained with CF₃‐CPHA. However, it is observed that CPHA possesses higher selectivity than CF₃‐CPHA.     

有机溶剂萃取野生枫香的鞣质及含量测定

目的：用四种不同有机溶剂萃取野生枫香（叶、枝）中的鞣质并测定其含量;方法：采用脂肪提取器回流提取和络合滴定法测定鞣质含量;结果：无水乙醇、乙酸乙酯、丙酮、石油醚提取枫香叶鞣质的含量为13.00%、11.99%、8.30%、4.35%.结论：表明无水乙醇提取枫香树叶中鞣质效果最好、含量最多,枝中含鞣质最少.     

凝胶挤出流延聚氟乙烯薄膜的研究

介绍了一种适合聚氟乙烯薄膜生产制造的新工艺——凝胶挤出流延法。该工艺克服了聚氟乙烯自身结构特性给成型带来的困难,得到的薄膜产品具有耐候性强、强度高、透光率大等优点,并有很好的应用前景。此外还系统讨论了树脂结构、潜溶剂及加工条件对薄膜制品的影响。     

ALKYD PAINT WASTE CHARACTERIZATION AND DISTILLATION

In the present study the characterization and distillation of alkyd paint waste have been carried out in order to establish the technical viability of organic solvents recovery and to decide upon the best environmental management for the waste stream from a paint spray-booth application in an automotive component factory. The paint is a black primer based on an alkyd resin with toluene and xylene as solvents, black carbon as pigment, fillers, and other minor components.

The paint, paint wastes, and distillation wastes have been characterized by determination of the physicochemical properties of the solid (solvents content and flash point) and determination of ecotoxicity (EC₅₀), total organic carbon (TOC), and metals concentration of the leachates. The highly volatile matter (HVM) content, determined by the weight loss at 200°C, has been used as a parameter to relate with the hazardous wastes regulations based on the characterization parameters EC₅₀, TOC, and flash point.

Distillation experiments have been performed in a simple batch mode with mixtures of paint waste, water, and additives in order to obtain high efficiencies in the recovery of volatile organic compounds and to obtain a final solid with nonhazardous behavior and good manageability qualities. A fractional factorial design (2^3-1) of experiments was carried out in order to study the influence of the distillation variables: water/paint waste ratio (2/1-3/1 (g/g)), temperature (110°-145°C), alkaline additives (Na(OH),CaO, Ca(OH)₂), and amount of other additives (wt.% of bentonite, cement, and Ca(OH)₂) on the solvent recovery, [% VOCs]_Recovery, on the residual volatile organic compounds, [% VOCs]_{Distillation Waste}, and on the total organic content (TOC) of the waste leachates. The present work shows the quantitative results of the alkyd paint waste distillation process under optimum conditions.     

The treatment of waste-air containing mixed solvent using a biofilter 2. Treatment of waste-air containing ethanol and toluene in a biofilter

An experiment for five stages of a biofilter-run was performed to investigate the effect of hydrophilic ethanol and hydrophobic toluene on the biodegradation of hydrophobic toluene and hydrophilic ethanol, respectively, when waste-air containing toluene and ethanol was treated by a biofilter. Removal efficiencies of toluene and ethanol began to decrease when inlet load surpassed 90 g/m³/h and 100 g/m³/h consistent with maximum elimination capacities of toluene and ethanol, respectively. At the end of the biofilter-run, removal efficiencies for toluene and ethanol were decreased and maintained at 65% and 40%, respectively. The concentration of toluene at 1st sampling port was raised by factor of two in the 3rd stage of the biofilter run when the inlet load of ethanol co-feed was increased by 1.5 times, while the process conditions of toluene were maintained the same as those of the 2nd stage of biofilter-run. According to the result of Mohseni and Allen, it may be interpreted that removal efficiency of hydrophobic toluene was affected by the presence of hydrophilic ethanol when high load of hydrophobic toluene was applied like that of the 1st sampling port of the biofilter. However it was not the case when a low load of hydrophobic toluene was applied like those of the 2nd, 3rd and 4th sampling ports since hydrophobicity of toluene is much less that of α-pinene. Thus, it may be suggested that biodegradation of hydrophobic VOC was interfered by hydrophilic VOC dissolved in the biolayer and the degree of interference was proportional to the inlet load of hydrophobic VOC as well as that of hydrophilic VOC and was inversely proportional to the solubility of hydrophobic VOC. However, it was inferred that the existence of hydrophobic toluene from waste-air can hardly inversely hinder the removal of hydrophilic ethanol in the biofilter when timeevolutions of hydrophilic ethanol concentrations of this experiment were compared with those of the previous experiment of biofilter to treat waste-air containing ethanol only.     

Influence of operation parameters on the separation of mixtures by pervaporation and vapor permeation with inorganic membranes. Part 1: Dehydration of solvents

The separation performance of two different commercially available tubular inorganic membranes was studied for solvent dehydration. The separation layers consisted of A-type zeolite and microporous silica. The membrane characteristics were determined as function of operating conditions such as feed composition, temperature, and permeate pressure in pervaporation and vapor permeation. Among different membranes of the same batch, flux and selectivity were reproducible within 10%. The partial flux of water as the preferentially permeating component increases linearly with the water vapor pressure difference between feed and permeate and depends only marginally (viscosity influence) upon the properties of the organic component. The flux of the organic (retained) component is low and can best be described by assuming a substance and membrane specific permeance (flux over partial pressure difference) that is independent of composition. At very low water concentration in the feed one would expect a strong increase in permeability of the retained component through non-zeolite pores and larger silica pores as predicted by pure component measurements. However, this effect was not observed in mixtures within the concentration range studied here. A temperature rise improves flux rates exponentially while selectivity remains high. Thus, higher module cost in comparison to polymeric membranes can be compensated by reduced membrane area if a higher operating temperature can be chosen. Flux and selectivity decline as a function of permeate pressure with decreasing driving force. In vapor permeation with inorganic membranes superheating of the vaporous feed improves their performance while for polymeric materials a steep flux decline is observed. High flux and selectivity are obtained in the separation of water from alcohols. The normalized flux values of the A-type zeolite membrane are roughly 10 kg/m² h bar with a mixture selectivity of 2000 for methanol, 4000 for ethanol and 8000 for n-butanol. The average permeance of the amorphous silica membrane lies above 12 kg/m² h bar with mixture selectivity of 50 for methanol, 500 for ethanol and 2000 for n-butanol. The separation mechanism is mainly based on adsorption and diffusion enhanced by shape selectivity and size exclusion in some cases. The transport characteristics could be described with a simple transport model based on normalized permeate fluxes. With regard to the operation stability of the membranes, no deterioration of the performance was observed for the A-type zeolite in solvent dehydration or in separation of water from reaction mixtures. The silica membrane showed an initial conditioning effect involving a rearrangement of Si-OH groups with an increase in selectivity and decrease in flux of about 30%. After a few hours the performance stabilized and remained constant during further operation.     

Transport of lithium through a supported liquid membrane of LIX54 and TOPO in kerosene

A mathematical transport model is developed for the extraction of lithium from dilute synthetic solution, simulating geothermal water, using a supported liquid membrane (SLM) of LIX54 (major component is -acetyl-m-dodecylacetophenone) and TOPO (tri-n-octylphosphine oxide) in kerosene. The model is based on fundamental mass transfer and kinetics mechanisms that account for all possible transport resistances. The model is solved numerically and is used to investigate the effect of various extraction conditions and membrane support characteristics. Reasonable agreement is found between the predicted and the experimental results reported in literature.     

“鱼促Ⅳ”生产中的溶剂回收

本文介绍了在鱼生长促进剂Ⅳ号研制中,环氧氯丙烷等溶剂在缺乏平衡数据情况下,用精馏加以分离回收的方法.