Measurement of constant drying rate of wet material placed in a fluidized bed of inert particles under reduced pressure

The objective of this study is to estimate the drying characteristics of a relatively large material immersed in a fluidized bed under reduced pressure by measuring the constant drying rate. The constant drying-rate period in a fluidized bed under reduced pressure is difficult to measure because it is extremely short. To maintain the constant drying-rate period, distilled water is directly supplied to the drying material. Through our experiment, the heat transfer coefficient of the material surface was also determined. The results were compared with data on hot air drying. The constant drying rate is higher for fluidized bed drying than for hot air drying. It suggests that the heat transfer coefficient on the surface of the drying material is much larger for fluidized bed drying than for hot air drying. For fluidized bed drying, the effect of pressure in the drying chamber on the heat transfer coefficient is slight at the same normalized mass velocity of dry air (G/G_mf). The temperature difference between the inside of the drying chamber and the drying material is much smaller for fluidized bed drying than for hot air drying. The constant drying rate increases as the pressure in the drying chamber decreases.     

焦化高压氨水泵出口压力降低原因分析及处理

针对生产中高压氨水泵出口压力降低的现象,分析了原因,提出了改进措施。通过采取清理高压氨水槽、改造进口管、更换填料和终端阀门等措施,解决了压力降低的问题,确保了无烟装煤效果。     

Lipase-mediated synthesis of neopentyl glycol diester using a combination of reduced and standard pressure

Neopentyl glycol (NPG) diester is a biodegradable lubricant used in the machinery industry as it is suitable for the low-temperature environment. NPG diester was successfully synthesized with fatty acid and NPG using immobilized lipase. Immobilization was carried out with a liquid enzyme, Eversa® Transform 2.0 (from Thermomyces lanuginosus) and Lewatit VP OC 1600 as a carrier. The Eversa immobilized lipase prepared in this study was compared with commercial lipases, such as Novozym 435, Lipozyme RM IM, and Lipozyme TL IM. The Eversa immobilized lipase was the most effective biocatalyst for the synthesis of NPG diesters. The effects of enzyme loading and temperature on conversion were explored at a standard pressure of 101.3 kPa. And then, the effect of reduced pressure was investigated in the range of 1.3 to 40.0 kPa under optimum conditions obtained at standard pressure. The maximum conversion of ca. 63% was achieved at the optimal temperature of 50°C and the enzyme loading of 5% (based on the total weight of the substrate) at standard pressure after 10 h. However, the conversion to NPG diester increased markedly up to 97% after 10 h, even though reduced pressure as low as 26.7 kPa was applied. No significant differences in the conversion to NPG diester between the reactions at constant reduced pressure and the combined reaction of reduced pressure and standard pressure were observed. This pressure combination method employed in this study demonstrated a novel, energy-saving strategy for the synthesis of NPG diester.     

锅炉给水泵的改造

针对锅炉给水泵出口压力不足的问题,提出对锅炉给水泵叶片尺寸的改进措施,达到了预期效果。     

高压水射流喷嘴效率解析

在高压水射流清洗机械中,整机重量约有2 000～3 000kg,可是它的主要工作机构喷嘴的直径和长度只有2～3cm,其重量也就100～200g.但是高压水射流却完全是从这里产生的,因此喷嘴的效率分析就显得非常重要.     

Cake properties of nanocolloid evaluated by variable pressure filtration associated with reduction in cake surface area

A potential method has been developed for evaluating simultaneously both the average specific resistance and average porosity of the filter cake formed in unstirred dead‐end ultrafiltration of nanocolloids such as bovine serum albumin solution and silica sol. The method consists of variable pressure filtration followed by constant pressure filtration. The relation between the average specific cake resistance and the pressure drop across the cake was determined from the evolution of the filtration rate with time in the course of the variable pressure filtration period, based on the compressible cake filtration model. The average porosity was evaluated from the significant flux decline caused by a sudden reduction in the cake surface area in the middle of the constant pressure filtration period. The pressure dependences of both the average specific cake resistance and average cake porosity were obtained from only two runs which differed from each other in the pressure profiles. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3869–3877, 2014     

催化裂化降烯烃废催化剂磁分离回收工艺

本项研究采用永磁强磁场技术研制出了具有高磁感应强度的小型磁分离试验装置。利用该装置进行了FCC降烯烃平衡催化剂磁分离工艺条件考察试验,同时还对磁分离样品进行了FCC小型提升管对比评价试验。试验结果表明该技术处于国内领先水平。     

Drying characteristics of porous material immersed in a bed of hygroscopic porous particles fluidized under reduced pressure

A relatively large wet material was immersed in a fluidized bed of hygroscopic porous particle (silica gel beads) under reduced pressure. And then the drying characteristics were compared with those in the case of inert particle (glass beads). The comparison of drying characteristics is performed experimentally and theoretically. In calculation, the water transfer from the sample to the fluidized bed was considered. The calculation results are in good agreement with the experimental data. The effects of the operational conditions (the pressure in the drying chamber and the temperature of the drying gas) on the drying characteristics were also examined in both fluidizing particles.The drying finishes earlier in the case of hygroscopic porous particle than in the case of inert particle regardless of pressure in the drying chamber, since the water transfer from the sample facilitates the drying in the case of hygroscopic porous particles. The temperature decrement in drying appears in the case of inert particle. This phenomenon is also observed in the case of hygroscopic porous particle, but the decrement degree of the temperature is much smaller than that in the case of inert particle. The difference of the minimum temperature in the sample in drying between the cases of hygroscopic porous particle and inert particle is very slight for different pressures in the drying chamber.     

煤粉加压密相输送系统研究现状及发展方向

为优化干法煤气化的煤粉密相输送系统,介绍了加压密相气力输送技术和基于散体力学理论的固体输送泵技术2种典型的煤粉加压密相输送技术,分析了2种典型技术的技术特征及气体加压密相输送技术中的关键问题,提出了干粉加压固体输送泵的发展方向。固体输送泵技术是未来煤粉密相输送的发展趋势。未来应加强国内散体力学的相关理论、数值及试验研究,包括散体静力学,散体动力学的相关基础研究;研究煤种、水分、粒径等参数与摩擦系数之间的函数关系,确定Stamet Pump及PWR针对国内煤种所能提供的最大输出压力;确定典型的Stamep Pump、PWR的XTL技术工业放大的瓶颈所在,提出切实可行的放大解决方案。     

Effect of precursor, ambient pressure, and temperature on the morphology, crystallinity, and decomposition of powders prepared by spray pyrolysis and drying

The effect of reactor pressure and temperature on the morphology, crystallinity, and decomposition behavior of various powders produced by spray pyrolysis or drying is investigated. Zirconia, magnesium sulphate, and sodium chloride powders are produced at the reactor pressures of 760, 400, 250, and 120 Torr, and at the reactor temperatures of 100 °C, 200 °C, and 400 °C. Zirconia and magnesium sulphate powders are spherical, whereas the sodium chloride powders are cubic. Regardless of the pressure, the powders produced at 100 °C and 200 °C appear solid, and powders produced at 400 °C are hollow and disrupted. The experimental data and the calculations indicate that the evaporation rate, which is a function of pressure and temperature, controls the solute distribution within the droplet and as such determines the morphology of the powders. In addition, the shape and morphology of the powders are strong functions of the precursor type. The decomposition and crystallinity of the powders are determined using XEDS and XRD analyses, respectively. The crystallinity and decomposition of the powders are weak functions of pressure and strong functions of temperature.     

Computation of the pressure on the surface of a plate hurled by explosion products under sliding detonation

Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 2, pp. 123–128, March–April, 1990.     

热泵工况下竖直不锈钢表面微生物污垢动态生长行为

城镇二级出水所含致垢微生物将导致其热能回用过程中在换热面上形成以微生物污垢为主的混合污垢,影响换热、流动效率。以可控微生物种类及浓度的模拟二级出水为介质,对典型热泵供暖、制冷工况下微生物污垢在模拟板式换热器的竖直不锈钢壁面上的形成过程进行了研究,关注起始阶段垢层微观结构演变与宏观垢量生长特性,并考查了流速、菌浓度对成垢过程的影响。实验表明：垢层微观结构演变与宏观垢量增长存在同步关系,污垢生长速率对应于微观结构演变;流速对于成垢过程影响呈非单调性;菌浓度低至10³ CFU·ml^-1（CFU,菌落形成数）时成垢量可忽略。实验结果可指导除垢时间点的选择及改进抑垢、除垢方法。     

大型熟料储库桩基侧压力计算的研究

本文对水泥工厂大型熟料储库的桩基在超重料压下的水平侧压力计算进行了探讨,给出了计算方法和公式,并对一些计算参数的取值提出了新的论点。     

压力反应釜中低温热裂解废旧LLDPE塑料制备PE蜡

以废旧线性低密度聚乙烯（LLDPE）为原料,采用压力反应釜在封闭条件下通过热裂解方法制备聚乙烯蜡（PE蜡）,研究了裂解时间、温度和压力对产物的产率、分子量和滴熔点的影响,并通过红外光谱对产物的官能团进行了分析。实验结果表明,在裂解时间为15~60 min,裂解温度约为260℃的条件下,LLDPE裂解所得到的PE蜡性能较佳,其主要成分为直链烷烃和烯烃,滴熔点大于100℃,黏均分子量处于1400~4700;由动力学分析可知,由于封闭反应体系增加了反应压力,降低了裂解温度和活化能,促进了LLDPE裂解反应进行,同时抑制了气体分子的产生,有利于获得PE蜡。     

Interaction of triflupromazine with distearoylphosphatidylglycerol films studied by surface pressure isotherms and cyclic voltammetry at a 1,2-dichloroethane/water interface

The effect of triflupromazine (TFP) on molecular packing of distearoylphosphatidylglycerol (DSPG), adsorbed at the water/1,2-dichloroethane interface, was investigated using cyclic voltammetry (CV) and surface pressure-molecular area isotherm. TFP partition in the DSPG monolayer changes the structure of the film. The results indicate that a fluidizing effect, dependent on the time and the drug concentration, takes place leading to an increase in the permeability of the film. This effect is produced by TFP either from the organic or from the aqueous phase due to the amphiphilic nature of this drug. Nevertheless, the expansion of the film is enhanced when TFP acts from the aqueous phase.     

Investigation of a new reactant for fluorinated polymer surface treatments with atmospheric pressure glow plasma to improve the adhesive strength

Poly(tetrafluoroethylene-co-perfluoro [alkyl vinyl ether]) (PFA) and polytetrafluoroethylene (PTFE) films were treated by three kinds of atmospheric pressure glow plasmas: an untreated sample was treated by He plasma or trimethoxyborane (TMB)/H₂/He plasma, and a TMB-absorbed sample was treated by H₂/He plasma. TMB was a new reactant for the treatment, to increase the films’ adhesive strength with an epoxy glue. These films were also treated by a wet method using a sodium solution (Tetra-Etch compound) and such films were used as the control samples. The peel strength values of the controls of PFA and PTFE were 3.5 and 9.5 N cm⁻¹, respectively. The adhesive strengths of all plasma-treated PFAs were stronger than those of untreated one. Especially, the peel strength of the TMB/H₂/He plasma-treated PFA showed the maximum value of 4.5 N cm⁻¹, which was bigger than that of the control one. The adhesive strength of the TMB/H₂/He plasma-treated PTFE films also showed the maximum peel strength, 7.9 N cm⁻¹, but this value did not exceed that of the control PTFE. Such results suggested that the TMB/H₂/He plasma had the advantage of providing better adhesive improvement of those polymers, especially PFA than the wet method could provide. The results of XPS and SEM indicated that TMB actively removed fluorine atoms from the polymer surface. Therefore, boron compounds are effective for the improvement of the adhesive strength between the fluorinated polymer and the epoxy glue.     

An analytical approach for the adhesion of a semi-infinite elastic body in contact with a sinusoidal rigid surface under zero external pressure

An analytical approach for the adhesion of a semi-infinite elastic body in contact with a sinusoidal rigid surface under zero external pressure is presented. Although Johnson (Int. J. Solids Struct. 32, 423 (1995)) has proposed an analytical solution for a slightly wavy surface, while Zilberman and Persson (Solid State Commun. 123, 173 (2002); J. Chem. Phys. 118, 6473 (2003)) have given a numerical solution for a highly wavy surface by considering the curvature of the contact area in the calculation of the interfacial term of the total energy, our solution is not only for small amplitude of roughness (i.e., the slightly wavy surface as Johnson's) but also for large amplitude of roughness (i.e., the highly wavy surface as of Zilberman and Persson). Our solution considers the curvature of the contact area as do Zilberman and Persson. Our results which are obtained for the total energy and equilibrium condition of the system agree with both Johnson's and Zilberman and Persson's results. The effects of the material constants and the surface roughness on the adhesion are clearly expressed and discussed.     

Investigation of the intra-particle sintering kinetics of a mainly agglomerated alumina powder by using surface area reduction

An alumina precursor was prepared by the aluminium sulphate (0.20 M) and excess urea reaction in boiling aqueous solution. The precursor was calcined at 900 °C for 2 h and then δ-Al₂O₃ powder having volumetric agglomeration degree of 80% was obtained. Cylindrical compacts having diameter of 14 mm were prepared under 32 MPa by axial pressing using oleic acid as binder. Each compact was fired isothermally at various temperatures between 950 and 1400 °C. The firing time was changed from zero to 2 h. The fired compacts were examined by scanning electron microscopy (SEM) and nitrogen adsorption techniques. The specific surface areas (S/m² g^− 1) of the samples were calculated using the Brunauer, Emmett, and Teller (BET) procedure. The rate constant (k) and mechanism-characteristic parameter (n) were obtained for different temperatures between 950 °C and 1150 °C from the application of the neck-growth sintering rate (NGRM) model on the surface area reduction data. An Arrhenius equation and the parameter n for the sintering were found in the forms of k = (7.648 × 10⁶ h^− 1) exp (− 186,234 J mol^− 1 / RT) and n = 4.0 × 10^− 7 T³-1.7 × 10^− 3 T² + 2.3 T − 1030.8 respectively. The parameter n changes in the interval 0.61 <  n < 1.34 with rising temperature having maximum at about 1025 °C. Based on the SEM images and NGRM data, the intra-particle sintering was discussed.     

Towards a determination of the active surface area of polycrystalline and nanoparticle electrodes by Cu upd and CO oxidation

Methods for the determination of the surface area for Pt, Ru and Se modified Pt and Ru are compared, in view of their possible application for technical and nanoparticle electrodes. The hydrogen adsorption charge can hardly be used as a reliable measure for the surface area for Ru because it is paralleled by anion adsorption. The charge necessary for the oxidation of adsorbed CO also contains a large contribution due to anion or oxygen adsorption, which amounts to approx. 45% of the charge in the case of Ru. The mass spectrometrically determined amount of CO₂ formed gives a more reliable measure for the surface area, provided that the maximum coverages are constant and independent of the particular surface. Values obtained in this way agree to within 20% with surface area values obtained from measuring the charge needed for the desorption of a complete monolayer of Cu upd on Pt(111) and polycrystalline Pt, polycrystalline Ru, submonolayers of Ru on polycrystalline Pt and on Pt(111) and for nanoparticle, carbon supported electrodes. Se modified Ru has recently found attention as a methanol tolerant cathode material for oxygen reduction. CO does not adsorb on Pt or Ru saturated by Se. For surfaces partially covered by Se, a comparison of the charge measured by cyclic voltammetry in the hydrogen region and of the mass spectrometrically determined amount of CO₂ suggests that the latter can be used for a determination of the area not covered by Se. Cu upd, on the other hand, also takes place on surfaces completely covered by Se; the Cu desorption charge is independent of the Se coverage on Pt and Ru modified Pt as long as it does not exceed 70% of full coverage. In the presence of multilayers of Se, Cu _x Se is formed. On Se modified bulk Ru the amount of Cu upd decreases with increasing Se coverage, approaching only 105 μC m⁻² for full Se coverage.