Abtrennung und Extraktion von Bleicherde in geschlossenen Filtern

Separation and Extraction of Bleaching Earth in Closed Filters Application of closed disc filters with centrifugal discharge in filtration and extraction of bleaching earth is described. This type of filter offers advantages, amongst others, those due to exclusion of air and the possibility of extraction of oilcontaining bleaching earth cake “in situ”. Short time interval between starting up and emergence of clear filtrate, and optimum capacities are attained, if pore size of filter membrane is chosen at two to four times the average particle size of solids. Traces of soap contained in the oil have undesirable effect on rate of filtration. It is advantageous to carry out the extraction in two stages, namely, first with dilute miscella, and then with pure solvent. A good quality extracted oil is obtained with hexane as solvent. A combined filtration and extraction plant, attached to an edible fat refinery, consists of 6 filters, each having 20 m² filtration surface. A plant for miscella distillation, and an inert gas plant for generation of protective gas used for compressing, are connected as well. The process is controlled by programmed operation. Filtration capacity of cottonseed oil with 1% bleaching earth with subsequent extraction of filter cake is 340 1/m² · h.     

Körnungsaufbau und Filtrationseigenschaften von Tonsil-Bleicherden

Particle Structure and Filtration Properties of Tonsil Bleaching Earths The particle structure of bleaching earths influences the bleaching process of oils and fats both during adsorption and filtration. The adsorptive properties of a bleaching earth are improved with decrease in particle size, but the filtration properties are impaired. The bleaching earth must have an optimum particle composition in order to ensure good adsorption and rapid filtration yielding a clear filtrate. In this context, the difficulty in the determination of particle size distribution of bleaching earths is emphasized. Moreover, the influence of water content of Tonsil bleaching earths and that of the amount of bleaching earth used the filtration and adsorption is reported. Possible alterations in the particle composition of bleaching earths during transport or pumping in admixture with oils or fats are discussed.     

自动反冲洗过滤器在石蜡加氢装置中的应用

抚顺石化公司石油一厂高压石蜡加氢装置所用的原料过滤器为手工蒸汽吹扫型过滤器,实际使用中存在诸多问题.搬迁建设中,经调研了解并综合各方意见,决定改用自动反冲洗型过滤器,其与原用过滤器相比,具有自动化程度高、过滤精度高、劳动强度低等优点,在燕山石化炼油一厂石蜡加氢精制装置的实际应用中已显示出了它的优越性.     

炼油污水处理装置优化技改与运行

某炼油污水处理厂均质单元、气浮单元、砂滤单元由于进水水质、流量的变化以及工艺落后等原因已经不能满足处理要求,影响了处理厂整体的处理量和处理效果。通过拆除均质罐内固定收油系统,安装浮动环收油器;将一级气浮工艺中的部分溶气气浮法改为涡凹气浮法;拆除砂滤池,安装连续动态絮凝砂滤机,对以上3个单元的工艺进行优化改造,使处理水量和处理效果均得到了大幅提升,同时减少了加药量,降低了运行能耗。     

Five years experience in VTE industrial operations and their design improvements

The purpose of this paper is to report the experiences gained over five years of industrial run and to highlight the new development of Snamprogetti VTE. Our experiences are related to the desalination unit having a capacity of 1440 m³/day installed in the I.P. refinery in Taranto. This plant was started in March 1978 and since then it has supplied all the distilled water required for the refinery. An acid cleaning has been so far carried out every year and always during the shut downs for refinery maintenance. During said shut downs it was also possible to inspect the plant so as to check its conditions which proved to be good, showing the surfaces free both from corrosion and scaling. Until now the average on stream factor, taking into account the period of acid cleaning, has been about 90% and the production rate, due to the refinery demands, over 80% of the nominal design capacity. Thanks to the good performances of this plant, I.P., owner of the refinery, requested Snamprogetti to build a new desalination unit.     

Dewatering of coal plant tailings: Flocculation followed by filtration

A sustainable alternative to tailings dam disposal of coal refuse is mechanical dewatering of tailings, which provides fast production of dry solids and water reuse. In this study, flocculation followed by filtration of coal plant tailings, a new concept in tailings dewatering is investigated in detail. This paper focuses on the effect of preconditioning tailings with varying flocculants and dosages on filtration kinetics and the resultant moisture content of the filter cake. The results show that the cationic flocculant, MAGNAFLOC LT 425, requires a high dosage to produce a low moisture content filter cake and clear filtrate. Optimal sized flocs were produced with the anionic flocculant, MAGNAFLOC 5250, even though the particles are negatively charged. The kinetics of the filtration was dependent on the composition of process water as indicated by supporting sedimentation tests. The concentration of divalent alkali earth metals such as Ca²⁺ and Mg²⁺ allow for large floc growth by a bridging mechanism, which involves binding of the polymer and the negativity charged particle. Filtration and settling curves at this dosage were also supported by filter cake analysis using Darcy plots. It was found that the large floc size significantly increases the permeability of the filter cake. Floc size measurements and fractal dimension showed that while the large flocs were produced with anionic flocculant, the flocs produced with the cationic flocculant were small and weak. The results indicate that the optimum dosage and flocculant type for effective and efficient filtration of coal plant tailings is approximately 350 g/t of anionic flocculant at a 35% solids content and 40 kPa filtration pressure.     

Regeneration of a spent bleaching earth and its reuse in the refining of an edible oil

A spent bleaching earth from an edible oil refinery has been regenerated by thermal processing followed by washing with a solution of hydrochloric acid. Optimal regeneration conditions have been controlled by decolorization tests of a degummed and neutralized crude edible oil. Optimal values (temperature: 500 °C, carbonization time: 1 h, HCl concentration: 1 M ) gave a material as efficient as a virgin bleaching earth. The percentage uptake of chlorophyll derivatives and β‐carotenoids calculated at 410 and 460 nm, are respectively 92.8 and 95% for an oil processed by the regenerated spent bleaching earth, against 77.4 and 92.7% for the same oil processed by a commercial virgin bleaching earth. The results obtained after decolorization of an edible oil with a regenerated spent bleaching earth indicate that during the process, the resultant oil did not undergo any changes in the iodine value, the free fatty acid content and the saponification value. © 2000 Society of Chemical Industry     

Regeneration of oils used for deep frying: A comparison of active filter aids

A number of products are promoted for the purpose of regenerating used frying oils. These materials are referred to as “active” filter aids. They are purported to adsorb polar compounds, which are the products of oil degradation, and to retain them for removal by filtration. To evaluate some of these materials, portions of a used oil were treated with each of several “active” filter aids and filtered in a commercial-type recirculating oil filter. The triglycerides and any adsorbed compounds were extracted from the filter cake with a series of increasingly polar organic solvents. The composition of each of the filter cakes was quantitatively determined. The materials tested in this study were diatomaceous earth, acid-activated bleaching earth, activated aluminas, silica, carbon and synthetic magnesium silicate. Significant differences in the adsorbent characteristics of the materials were found. Adsorption of polar oil degradation compounds ranged from 2 mg of polar compounds per gram of diatomaceous earth to about 200 mg/g magnesium silicate.     

Control of grain boundary in alumina doped CCTO showing colossal permittivity by core-shell approach

Grain boundaries of CaCu₃Ti₄O₁₂ (CCTO) materials have been shown to play leading role in colossal permittivity. Core-shell design is an attractive approach to make colossal dielectric capacitors by controlling the grain boundaries. Core-shell grains of CCTO surrounded by Al₂O₃ shell were synthesized by ultrasonic sol-gel reaction from alumina alkoxide precursor. The influence of alumina shell by comparison with bare CCTO grains was studied. Particularly, microstructure, dielectric and electric effects on sintered ceramics are reported. The average grain size and the density are increased compared to undoped CCTO leading to an improvement of permittivity from 58,000 to 81,000 at 1?kHz. Furthermore a decrease of dielectric loss is found in a frequency range of 10²–10³?Hz. Moreover, the activation energy of grain boundaries is increased from 0.55 to 0.73?eV and the electrical properties such as breakdown voltage, non-linear coefficient and resistivity are improved with the aim of making industrial capacitors.     

Influence of electric field strength on structure,microstructure, and electrical properties of flash sintered 8% mol Yttria-stabilized zirconia as a solid oxide fuel cell electrolyte

To study the effect of electric field on the characteristics of flash sintered materials, 8% mol. Yttria-stabilized zirconia (8YSZ) was isothermally flash sintered under various electric field strengths as a solid oxide fuel cell (SOFC) electrolyte. Structural, microstructural, and electrical characteristics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Electrochemical impedance spectroscopy (EIS), respectively. Results show that the electric field did not affect the relative density of flash sintered 8YSZ. Electric fields stronger than 300 V cm^?1, however, transformed the cubic structure to tetragonal. Microstructural studies show that the average grain size of samples is independent of the applied electric field strength. Electrochemical impedance spectroscopy showed changes in the grain boundary characteristics upon using the electric field for flash sintering. Oxygen vacancy concentration in the grain boundary of flash sintered samples was more than ten times higher than conventionally sintered ones, which improved the conductivity in flash sintered samples.     

Bleaching of Olive Oil by Membrane Filtration

In this study the application of membrane processes for olive oil bleaching is investigated. Olive oil is treated by adding 0.7 wt% of bleaching earth, 0.3 wt% of activated charcoal, and 5% wt% of sodium dodecyl sulfate solution (0.05 m ) and then charged into the membrane cell. Operating conditions including pressure ((2?4) × 10⁵ Pa), temperature (25–45 °C), and stirring rate (100–300 rpm) are optimized. Physico‐chemical properties of membrane bleached oil are evaluated and compared with crude and industrially bleached olive oil. Results show that the filtration conditions for the optimized point are as follows: pressure = 3.7 bar (3.7×10⁵ Pa), temperature = 36.5 °C, and stirring rate = 300 rpm. Under optimum conditions, the amounts of carotenoid and chlorophyll contents are decreased (71.3% and 40.42%, respectively). Acidic and thiobarbituric acid values reduction in membrane‐processed oil (12.42% and 14.46%, respectively) are more than the industrial one. Also, some bioactive compounds such as sterols and phenolic compounds are increased in the membrane‐filtered sample (23.13% and 57.12%, respectively). Practical Applications: Olive oil bleaching is an important step along the refining process. Pigments and minor impurities that reduce olive oil stability are removed in this step. Given the disadvantages of conventional bleaching, alternative methods are introduced. In this study, the effect of membrane filtration on olive oil color is studied. Because of the mild operating conditions, the reduction of clay percentage, as well as the increase of bioactive compounds in optimum conditions, this method has the potential to be a good alternative to conventional bleaching processes.     

Implications of particle size to transient stage of deep bed filtration

This study was aimed at investigating the effect of particle size, mostly in the submicron range, on break-through stage of filtration. Latex beads, with diameters ranging from 0.46- to 2.967-μm were filtered through filter grains of diameters 0.1-, 0.175- and 0.45-mm. Experimental conditions were chosen so as to obtain breakthrough curves. The experimental results showed that the initial efficiency follows the pattern reported by previous experimental and theoretical studies, i.e., lower efficiency for 0.825-μm particles which fall in the range of critical size. However, the particle removal during the transient stage increased with an increase in particle size for the range of sizes studied. This pattern is qualitatively confirmed by the theoretical predictions of Vigneswaran and Chang (1986) model. This study also provides experimental verification of the effect of the ratio of particle size and grain size at different stages of filtration.     

Cross-flow separation of yeast cell suspensions using a sintered stainless steel filter tube

A new design of cross-flow filtration unit, the Transep filter, has been investigated for the separation of slurries of Saccharomyces cerevisiae. Porous cylindrical sintered stainless steel tubes of 2 μm and 3 μm nominal pore size ratings were used as filter media. Filtration rates were measured for cell suspensions ranging from 3 to 25 kg m^?3. The 3 μm filter produced particle-free filtrates at average rates from 1.25 m³ m^?2 h^?1 which declined to half this value over the range of cell concentrations studied.     

The performance of pumice as a filter bed material under rapid filtration conditions

Deep bed sand filters are used extensively in drinking water and wastewater treatment. In this study, sand and pumice were used as a filtration media under rapid filtration conditions and performance results for both were compared. Turbidity removal performance and head losses were investigated as functions of filtration rate, bed depth and particle size. Under the same experimental conditions such as 750 mm bed depth, 7.64m³/m².h flow rate and, 0.5−1.0 mm grain size, turbidity removal rates for sand and pumice were found to be 85-90% and 98-99%, respectively. Furthermore, the head loss for sand and pumice were found to be 460 mm and 215 mm, respectively. The results obtained have shown that pumice has a high potential for use as a filter bed material.     

Have Abrasive Liquid Filtration Applications Met their Match with TufTex Filter Media?

In many industrial liquid filtration applications filter media can be subjected to a severe abrasive loading that can limit their operating lifetime, and therefore result in increased plant downtime and reduced process efficiency. Madison Filter Ltd, UK, has developed a solution to such abrasion problems. Tuf-Tex^™ is a patented treatment that can be applied to standard textile based filter media to increase abrasion resistance. Professor Richard Lydon, Richard Allan & Joseph Johnson discuss the treatment technology and present both laboratory and field performance data.     

Electric field-assisted flash sintering of tin dioxide

SnO₂ green pellets were submitted to ac electric fields at temperatures below 1350 °C. Electric current pulses occurred and a substantial modification was found in the microstructure of the pellets after application of 80 V cm⁻¹ at 900, 1100 and 1300 °C. Similar experiments were carried out in SnO₂ mixed to 2 wt.% MnO₂. The linear shrinkage of the pellets was monitored with a dilatometer during the application of the electric field. Scanning electron microscopy micrographs of the pellets show the grain structure evolution after the electric current pulses. The larger is the electric current flow through the SnO₂ pellet, the larger are the shrinkage and the average grain size. Even though sintering occurs without significant densification in SnO₂, the welding of the grains is evident. The apparent density of green pellets of SnO₂ with MnO₂ addition sintered at 1100 °C increased 110% with the application of 80 V cm⁻¹, 5 A.     

Process Modelling of Combined Degumming and Bleaching in Palm Oil Refining Using Artificial Neural Network

Combined degumming and bleaching is the first stage of processing in a modern physical refining plant. In the current practice, the amount of phosphoric acid (degumming agent) and bleaching earth (bleaching agent) added during this process is usually fixed within a certain range. There is no system that can estimate the right amount of chemicals to be added in accordance with the quality of crude palm oil (CPO) used. The use of an Artificial Neural Network (ANN) for an improved operating procedure was explored in this process. A feed forward neural network was designed using a back-propagation training algorithm. The optimum network for the response factor of phosphoric acid and bleaching earth dosages prediction were selected from topologies with the smallest validation error. Comparisons of ANN predicted results with industrial practice were made. It is proven in this study that ANN can be effectively used to determine the phosphoric acid and bleaching earth dosages for the combined degumming and bleaching process. In fact, ANN gives much more precise required dosages depending on the quality of the CPO used as feedstock. Therefore, the combined degumming and bleaching process can be further optimised with savings in cost and time through the use of ANN.     

循环生物曝气滤池和过滤组合工艺处理炼油轻度污染废水

采用新型的循环生物曝气滤池（CBAF）和过滤组合工艺对炼油轻度污染废水进行净化回用工业试验。研究了填料粒径和高度、水力停留时间和溶解氧浓度对CBAF工艺处理效果的影响。结果表明CBAF工艺具有碳化作用、硝化作用和过滤作用。CBAF工艺净化该废水适宜的操作条件为：水力停留时间100 min,溶解氧浓度3 mg·L^-1左右,反冲洗周期2～3 d。炼油轻度污染废水经该组合工艺处理后,COD、石油类污染物、NH₃-N和SS平均去除率分别为62.6%、71.7%、92.6%和97.0%,出水COD、石油类污染物、NH₃-N和SS平均质量浓度分别为14.4 mg·L^-1、0.75 mg·L^-1、0.49 mg·L^-1 和2.4 mg·L^-1,经处理后出水水质达到工业回用水要求。     

Grain size variation in nanocrystalline silicon carbide irradiated at elevated temperatures

This study reports on ion irradiation-induced grain size variations in nanocrystalline SiC films on Si substrates. The SiC grains with average size ranging from ~2 to 20 nm were embedded in amorphous SiC matrices. Irradiation was performed using 5 MeV Xe²³⁺ ions to 1.15 × 10¹⁶ ions/cm² at 700 K. The irradiated films were characterized using X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Significant grain growth is observed for smaller grains that tend to saturate at ~8 nm. In contrast, irradiation of larger grains (~20 nm in size) leads to a decrease in the grain size, which could be associated with the production of lattice disorder within the grains. Homonuclear C-C bonds in the irradiated amorphous SiC matrix are found to be graphitized. This bonding transformation could limit or inhibit grain growth and contribute to the size saturation. The results from this study may suggest nanocrystalline SiC as a promising candidate structural or cladding material for applications in advanced nuclear reactors.     

Controlled Filtration of Waste Water Containing Fatty Matter

Wastes purification by “Ingram” controlled filtration process on tower packed with plastic packing called “panapak” had a new application in purification of waste water containing by-products of a vegetable oil refinery and chemical plant where BOD ranges from 5 000 to 19 000 and pH average 1.5. The biologically controlled filtration unit gives an effluent of BOD 50 by continuous operation.