致密储层束缚水干化反应及干化效应差异分析与评价

通过向致密储层中注入干化剂,使其与地层水发生干化反应能够消耗地层水、降低储层含水饱和度,从而提高气体渗流能力。以致密气藏干化原理为基础,对所选干化剂进行原理性干化实验发现,干化剂实际耗水量大于理论耗水量。分析认为,干化剂实际干化效果还受化学反应热效应的影响。本文以热化学理论为基础,研究了干化剂与水反应的热效应及其对干化效果的影响。并考虑到实际地层往往处于不同的温度和压力条件下,故对干化反应热效应随体系温度和压力的变化情况做了研究。结果表明,所选干化剂与水反应能够放出约5.28k J/g的热量,放出的热量能够使反应速率加快和使部分水分子蒸发成气相从而提高干化效率;干化剂化学反应热随温度和压力的升高而增加,但增加速率较小;温度和压力的变化对热蒸发耗水量影响较小。     

柳树河油页岩微波干燥及其对热解特性的影响

在对家用微波炉改造基础上搭建了微波干燥实验台,研究了柳树河油页岩微波干燥特性及对热解特性的影响。结果表明,微波干燥所需的时间为传统干燥所需时间的20%;微波干燥速率要明显大于传统干燥速率;Page模型适用于描写柳树河油页岩微波干燥过程。微波干燥的油页岩同热风干燥后及原样油页岩的热解活化能随转化率的变化曲线基本一致,整体呈先上升后下降的趋势,在转化率为0.7时达到最大值;热解活化能在80~200 kJ/mol变动;微波干燥油页岩热解反应有机质分解段的活化能增加。     

生物质微波干燥及其对热解的影响

通过与常规热风干燥方式比较,研究生物质微波干燥过程及其对热解的影响,以探索在生物质快速热解液化工艺中采用微波干燥技术进行原料预处理的可行性。干燥实验表明,微波炉的干燥速率明显大于烘箱（5倍以上）,同时在微波快速干燥过程中,原料内部的孔隙结构得到了改善。热天平上干燥样品的热解表明,微波干燥处理有利于生物质的热解,特别是纤维素和半纤维素的热解,并且能在一定程度上抑制生物油蒸汽的二次裂解反应,从而使实际流化床热解液化装置中的生物油产率有所提高。研究表明,将微波干燥技术用于生物质热解液化的原料预处理过程在技术上和经济上均具有可行性。     

Drying of alkoxide gels—Observation of an alternate phenomenology

The process of drying of a porous material as per the current phenomenological theory can be divided into two stages. At first the body shrinks by an amount equal to the volume of liquid that evaporates, and the liquid-vapor interface remains at the exterior surface of the body. The second stage begins when the body becomes too stiff to shrink and the liquid recedes into the interior, leaving air filled pores near the surface. We shall refer to this phenomenology as the drying front model. In our investigation of drying of alkoxide silica gels of less than 50 Angstroms pore radius, we have observed a different drying pattern, in which even after the gel body stops shrinking, drying continues to occur by evaporation on the exterior surface of the gel body, causing spontaneous nucleation of partially or fully dried opaque clusters, randomly distributed in the interior parts of the gel. These clusters than increase in number and size till they coalesce to form an opaque body. Upon further drying, the gel returns to its transparent form. We postulate that this is possible only if the rate of fluid flow in the pores by diffusion is faster than that by Darcy's flow, as well as the evaporation rate at the surface of the gel body. We shall refer to this as the cluster drying model. We shall present results of pin-hole drying experiments on cylindrical alkoxide gels showing that for identical gels the evaporation rate can be increased to change the phenomenology from cluster drying to one that exhibits both phenomenology simultaneously and finally to that of the drying front phenomenology. We shall also show the effect of gel pore size distribution on the phenomenology of drying under identical drying conditions. Finally, we will present evidence that for successful drying of large cylindrical alkoxide gels, drying conditions favoring cluster drying phenomenology is desirable.     

Assessment of the bioactive compounds,antioxidant and antibacterial activities of Isodon rubescens as affected by drying methods

The influence of natural drying (ND), hot-air drying (HD), vacuum drying (VD), infrared drying (ID) and freeze drying (FD) on bioactive compounds and bioactivities of Isodon rubescens (Hemsl.) was investigated in this study. The results showed that different drying methods resulted in the differences in bioactive compositions’ content, antioxidant and antibacterial activities of extracts from I. rubescens. FD sample possessed the highest content of total phenolics, total flavonoids and several main phenolic compounds, as well as the stronger antioxidant and antibacterial activities, followed by ND, HD and VD, the lowest for ID samples. For this reason, freeze drying would seem to be more advisable for the drying I. rubescens, and future studies could focus on the quality evaluation and optimising various drying parameters.     

(NH4)2MoS4在活性炭上浸渍过程的研究:Ⅱ.干燥机理及模型

（ＮＨ＿４）＿２ＭｏＳ＿４在活性炭上浸渍过程的研究Ⅱ．干燥机理及模型秦慧芳，张成芳，陆岗，俞丰，朱子彬（华东理工大学无机化工研究所，上海２００２３７）２３７）关键词硫代钼酸铵，活性炭，干燥，钼分布，干燥模型负载型催化剂的活性组分在载体上的分布，受浸渍...     

Integration of biomass drying with combustion/gasification technologies and minimization of emissions of organic compounds

Moisture content (MC) of green biomass or raw biomass materials (wood, bark, plants, etc.) commonly exceeds 50 mass % (wet basis). The maximum possible MC of biomass fuel for big scale combustion (e.g. fluidized bed combustion with low external heat losses) is approximately 60–65 mass %. Higher biomass MC generally causes operational problems of biomass combustors, lower stability of burning and higher CO and VOC emissions. Gasification of biomass with higher MC produces fuel gas of lower effective heating values and higher tar concentrations. In this review, various technological schemes for wood drying in combination with combustion/gasification with the assessment of factors for possible minimization of emissions of organics from the drying processes are compared. The simple direct flue gas biomass drying technologies lead to exhaust drying gases containing high VOC emissions (terpenes, alcohols, organic acids, etc.). VOC emissions depend on the drying temperature, residence time and final MC of the dried biomass. Indirect biomass drying has an advantage in the possibility of reaching very low emissions of organic compounds from the drying process. Exhaust drying gases can be simply destroyed as a part of the total combustion air (gas) in a combustion chamber or a gasifier. Liquid, condensed effluents have to be treated properly because they have relatively high content of organic compounds, some of them accompanied by odor. Drying of biomass with superheated steam offers more uniform drying of both small and bigger particles and shorter periods of higher temperatures of the dried biomass, particularly if drying to the final MC below 15 mass % is required. In practical modern drying technologies, biomass (mainly wood) is dried in recirculated gas of relatively high humidity (approaching saturation) and the period of constant rate drying is longer. Drying of moist wood material (saw dust, chips, etc.) is required in wood pellet production. Emissions of organics in drying depend on biomass properties, content of resins, storing time and on operational aspects of the drying process: drying temperature, drying medium, final MC, residence time, and particle size distribution of the dried biomass (wood). Integration of biomass drying with combustion/gasification processes includes the choice of the drying medium (flue gas, air, superheated steam). Properties of the drying media and operational parameters are strongly dependent on local conditions, fuel input of the combustion/gasification unit, cleaning of the exhaust drying media (gas, steam, wastewater), and on environmental factors and requirements.     

造纸污泥薄层干燥实验及动力学模型分析

通过造纸污泥薄层干燥实验,考察了温度对造纸污泥干燥特性的影响,引入薄层干燥模型对污泥干燥动力过程进行模拟。结果表明,泥层越薄和干燥温度越高,污泥干燥的速率就越快,当干燥温度从80℃上升到160℃时,相对应的最大干燥速率从0.008g/(g·min)上升到0.030g/(g·min);Modified page模型描述了薄层造纸污泥在烘箱中的干燥过程,应用Fick扩散模型,薄层造纸污泥在干燥温度为80℃～160℃时,有效扩散系数为2.2×10^-10m²/s~3.96×10^-10m²/s。通过Arrhenius方程建立温度和有效扩散系数之间的关系,得出水分扩散的活化能为9.435kJ/mol。     

工业废碱催化剂MA与煤混合浸渍干燥的研究

以转筒干燥方式考察了福建无烟粉煤与工业废碱催化剂MA同时进行混合浸渍与干燥脱水的过程，讨论了煤的粒径，干燥温度，时间、气速、转筒转速、催化剂含量和转筒处理量等因素对煤与催化剂混合浸渍与干燥过程的影响。研究表明采用转筒干燥的方式,进口干燥空气温度在80 ℃～160 ℃、转筒处理量为214 kg/m3·h～1834 kg/m3·h、干燥气速0.12 m/s～0.30 m/s、干燥时间20 min内，混合物料的湿含量可降至<5%，且催化剂与煤浸渍充分均匀，满足流化床操作的要求，实现了最佳的催化气化效果。基于实验数据拟合了煤和废碱催化剂转筒干燥的传热系数方程，通过物料与能量衡算，模拟了混合物料连续干燥时沿转筒的湿含量的变化。     

The experimental study and modelling the drying kinetics of mussels using ultrasound assisted vacuum drying

In the present study, chemical compositions, drying kinetics, quality parameters and energy consumptions for mediterranean or black mussel (Mytilus galloprovincialis) subjected to ultrasound assisted vacuum drying (UAVD) were analyzed between the range of 50–70 ​°C. During drying only falling rate periods were observed. Obtained conclusions demonstrated that the moisture content and drying rate were influenced by the ultrasound assisted vacuum drying method and the drying air temperature. The ultrasound assisted vacuum drying shortened the drying period and increased the effective moisture diffusivity (D_eff). Drying led to a considerable increasing of protein and fat content. Six well-known thin layer drying models were compared with regards to coefficients of determination. The Alibas model was selected as the best one. The activation energy was calculated as 3.80 ​kW/kg. High “L1" and low "ΔE" values were obtained for dried mussels. Using of ultrasound assisted vacuum drying technique resulted in very low energy consumption.     

Influence of drying methods on chemical compositions,antioxidant and antibacterial activity of essential oil from lemon peel

The influence of natural, hot-air and infrared drying on chemical composition and bioactivity of lemon peel essential oil are investigated in this study. The results showed that drying resulted in losses or increases of some components or production of some new substances, but the d-limonene (59.52–70.01%) was found as the main component of essential oil. Drying brought about decreases in the yield, antioxidant and antibacterial activity of essential oil. However, the natural drying had little effect, while the hot-air and infrared drying resulted in significant decreases in these parameters, especially at the higher temperature. The yield was the lowest under hot-air drying (60 °C) and decreased by 78%, while infrared drying (60 °C) sample exhibited the lowest antioxidant and antibacterial activities. Infrared drying was easier to lead to the decrease in bioactivity than hot-air drying at the same temperature. These results provided the theoretical basis for drying lemon peel.     

Colloidal transport phenomena of milk components during convective droplet drying

Material segregation has been reported for industrial spray-dried milk powders, which indicates potential material migration during drying process. The relevant colloidal transport phenomenon and the underlying mechanism are still under debate. This study extended the glass-filament single droplet drying technique to observe not only the drying behaviour but also the dissolution behaviour of the correspondingly dried single particle. At progressively longer drying stage, a solvent droplet (water or ethanol) was attached to the semi-dried milk particle and the interaction between the solvent and the particle was video-recorded. Based on the different dissolution and wetting behaviours observed, material migration during milk drying was studied. Fresh skim milk and fresh whole milk were investigated using water and ethanol as solvents. Fat started to accumulate on the surface as soon as drying was started. At the initial stage of drying, the fat layer remained thin and the solubility of the semi-dried milk particle was much affected by lactose and protein present underneath the fat layer. Fat kept accumulating at the surface as drying progressed and the accumulation was completed by the middle stage of drying. The results from drying of model milk materials (pure sodium caseinate solution and lactose/sodium caseinate mixed solution) supported the colloidal transport phenomena observed for the milk drying. When mixed with lactose, sodium caseinate did not form an apparent solvent-resistant protein shell during drying. The extended technique of glass-filament single droplet approach provides a powerful tool in examining the solubility of individual particle after drying.     

Texture modifications of silica-alumina gels by microwave drying

The porous texture of silica-alumina hydrogel can be taylored by controlling the operating parameters of the preparation process. As the drying drastically modifies the texture it is important to minimize pore volume and radius decreases. Owing to a low drying temperature microwave heating coupled with convective drying could be a way to preserve the hydrogel texture. Its effects have been studied and it appears that the characteristics of the air flow are the main parameters of this drying mode which does not present decisive advantages as compared with other drying modes.     

Nanofibrillar cellulose aerogels

Highly porous aerogels consisting of cellulose nanofibrils were prepared by dissolution/regeneration of cellulose in aq. calcium thiocyanate followed by regeneration and carefully controlled drying. The influence of drying method (regular freeze drying, rapid freeze drying, and solvent exchange drying) on resulting porosity was studied by electron microscopy and nitrogen adsorption. While regular freeze drying caused significant coalescence of microfibrillar units, solvent exchange drying gave highly porous aerogel composed of approx. 50 nm-wide cellulose microfibrils. Correspondingly, specific surface area of the solvent-exchange-dried aerogels ranged 160–190 m²/g, in contrast to 70–120 m²/g of regular freeze-dried materials. Rapid freeze technique using liquid nitrogen-cooled metal plate gave aerogel sheets with asymmetrical porosity, with the face contacted by copper having porous structure similar to those of solvent-exchange dried material.     

Effect of drying on porous silicon

The phase transition of a fluid - in particular water - confined in the pores of silicon during drying is studied. The influence of this process on surface size and porosity is discussed. Methods of air drying, supercritical drying and freeze drying are considered. This revised version was published online in July 2006 with corrections to the Cover Date.     

Understanding isothermal semicrystalline polymer drying: Mathematical models and experimental characterization

The drying mechanism of semicrystalline poly(vinyl alcohol) (PVA) was investigated. PVA samples of various molecular weights were crystallized by annealing at temperatures slightly above the glass transition temperature of PVA, and swollen in water for different time periods. The water volume fraction in the sample was measured using a buoyancy technique. The samples were dried in air at constant temperatures, and the drying kinetics were investigated using thermogravimetric analysis. The change in degree of crystallinity of the swollen polymer during drying was measured by differential scanning calorimetry (DSC) as well as by Fourier transform infrared spectroscopy (FTIR). The degree of crystallinity of the samples increased during drying, which in turn was found to alter the drying rate. The drying kinetics were faster at higher temperatures, for lower molecular weights, and for lower degrees of crystallinity. A mathematical model was developed to predict drying rates of semicrystalline polymers by considering the crystallization kinetics during drying. The model predictions included the thickness of the polymer sample, the degree of crystallinity of the polymer, and the water weight loss as functions of drying time. Model predictions were found to agree reasonably well with the experimental results. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2771–2780, 1998     

Evaluation of Innovative Dried Purée from Jerusalem Artichoke—In Vitro Studies of Its Physicochemical and Health-Promoting Properties

The present study aimed to evaluate the effect of Jerusalem artichoke processing methods and drying methods (freeze drying, sublimation drying, vacuum drying) on the basic physicochemical parameters, profiles and contents of sugars and polyphenolic compounds, and health-promoting properties (antioxidant activity, inhibition of the activities of α-amylase, α-glucosidase, and pancreatic lipase) of the produced purée. A total of 25 polyphenolic compounds belonging to hydroxycinnamic phenolic acids (LC-PDA-MS-QTof) were detected in Jerusalem artichoke purée. Their average content in the raw material was at 820 mg/100 g dm (UPLC-PDA-FL) and was 2.7 times higher than in the cooked material. The chemical composition and the health-promoting value of the purées were affected by the drying method, with the most beneficial values of the evaluated parameters obtained upon freeze drying. Vacuum drying could offer an alternative to freeze drying, as both methods ensured relatively comparable values of the assessed parameters.     

基于超高效液相色谱联用高分辨质谱自动解析方法的金银花不同加工方式分析

金银花干燥加工方式直接影响其药用价值及经济效益。 采用基于超高效液相色谱联用静电场轨道阱高分辨质谱的非靶向代谢组学技术结合化学计量学自动化数据分析策略,分析了不同加工方式对金银花中化学成分的影响。金银花样品经甲醇-水（8∶2,体积比）溶液超声提取30 min,两次离心后取上清液,以Waters Acquity UPLC HSS T3色谱柱（2.1×100 mm, 1.8 μm）分离,乙腈-水溶液（均含有体积分数0.1%的甲酸）进行梯度洗脱。高分辨质谱选择正离子扫描模式（ESI+）并采用FULL MS/DD-MS2（TOP4）模式完成数据采集。在自动化解析方法软件平台对仪器采集的原始信号直接解析,鉴定出绿原酸、芦丁和异槲皮苜等16种差异性化合物。在化学成分解析的基础上,利用层次聚类分析和主成分分析等方法评价了晒干、阴干、电热烘干、烘房烘干、热泵烘干和真空冷冻干燥这6种加工方式获得的金银花样品品质差异。真空冷冻干燥、烘房烘干和热泵干燥等加工方式能够获得外观特征优质的金银花。在真空冷冻干燥方式下,金银花样品中的抗氧化功能性成分能够得到更好的保存。     

Effect of Filtrated Osmotic Solution Based on Concentrated Chokeberry Juice and Mint Extract on the Drying Kinetics,Energy Consumption and Physicochemical Properties of Dried Apples

Background: Filtration of osmotic solution affects selective penetration during osmotic dehydration (OD), and after drying is finished, this can influence the chemical composition of the material, which is also modified by OD. Methods: Osmotic dehydration was carried out in filtrated and non-filtrated concentrated chokeberry juice with the addition of mint infusion. Then, this underwent convective drying, vacuum-microwave drying and combined convective pre-drying, followed by vacuum-microwave finishing drying. Drying kinetics were presented and mathematical models were selected. The specific energy consumption for each drying method was calculated and the energy efficiency was determined. Results and Discussion: The study revealed that filtration of osmotic solution did not have significant effect on drying kinetics; however, it affected selective penetration during OD. The highest specific energy consumption was obtained for the samples treated by convective drying (CD) (around 170 kJ·g⁻¹ fresh weight (fw)) and the lowest for the samples treated by vacuum-microwave drying (VMD) (around 30 kJ·g⁻¹ fw), which is due to the differences in the time of drying and when these methods are applied. Conclusions: Filtration of the osmotic solution can be used to obtain the desired material after drying and the VMD method is the most appropriate considering both phenolic acid content and the energy aspect of drying.     

A Simple and Effective Model for Modeling of Convective Drying of Sewage Sludge: The Reaction Engineering Approach (REA)

Sludge drying is an essential step to reduce the cost of waste treatment but design of sewage sludge dryer is still relatively complicated since the drying kinetics is influenced signficantly by shrinkage, cracking and skin formation which occur during drying. In this study, the REA (reaction engineering approach) is implemented for the first time to model the convective drying of sewage sludge, a highly shrinkable material. The equilibrium activation energy (ΔEv,b) is evaluated according to the corresponding drying air humidity and temperature. This is combined with the relative activation energy (ΔEv/ΔEv,b), generated from one accurate drying run to produce the activation energy, which describes the internal behavior of the samples during drying. A good agreement between experimental and predicted data is observed. The REA is shown to perform comparable or even better than the classical diffusion-based model. It can be said that the REA can model the convective drying of sewage sludge well. The REA can be implemented for further applications including design and evaluation of sludge dryer.