双氧水生产系统工作液性质影响因素的探讨

分析了蒽醌法生产双氧水工艺中污水系统、白土床氧化铝粉以及工作液清洗对工作液性质的影响,提出了相应的处理措施。     

双氧水中总碳含量的影响因素及优化措施探讨

以3套蒽醌法双氧水装置为例,分析了影响双氧水总碳含量的因素,并提出了相应的优化措施。双氧水总碳含量包括双氧水中溶解有机物和游离有机物的含量。双氧水中有机物溶解量主要与工作液组分有关,通过常规的工艺控制难以有效降低。双氧水中游离有机物主要是萃取净化过程中夹带的少量有机物,其含量受净化塔净化能力、白土床再生能力,以及存储方式影响。通过采取定期补加芳烃萃取剂,提高净化塔塔身高度,在固定床床层中间增设一组分布器,增加白土床装填量,在双氧水储罐内增设氮气搅拌等措施,双氧水总碳含量明显下降,控制在280 mg/kg以下。     

5A、13X与NaLSX分子筛吸脱水实验研究

比较不同类型的分子筛吸水与脱水性能,筛选最优的分子筛脱水干燥剂。建立一种分子筛有效吸附水、有效脱附水与有效残留水的计算方法,比较在不同温度下的水含量分布。随脱附温度升高,分子筛有效脱附水增加,有效残留水减少,吸水率增大;真空气氛脱附后分子筛吸脱水能力优于非真空空气气氛吸脱水能力;在脱附温度为250℃时,13X与NaLSX的有效残留水为2.0%左右,5A分子筛的有效残留水基本完全脱除;当正常工作脱附温度为200～250℃时,13X分子筛脱附再生后的吸水能力最强,是最优的脱水干燥剂。     

双氧水生产原料的再生处理分析

对双氧水的性质与用途进行了简要说明,并对双氧水生产原料“工作液”再生处理的意义与工作液选择标准进行了分析,最后讨论了工作液的再生处理技术,这些技术可以提升双氧水的生产效果和生产质量。     

浅论工作液对双氧水生产的影响

江西昌九昌昱化工有限公司拥有二套1万吨／年和一套4万吨／年的双氧水装置,自1995年开始从事双氧水生产已十多年,其间有众多的疑难问题,特别是2005年下半年出现频繁堵塞氢化液过滤器的现象,造成只能低负荷生产、工作液组份中蒽醌含量无法往上提、系统降解严重,最后靠更换触媒和大量清洗工作液才得以解决。由此可见工作液的好坏直接影响双氧水的生产和安全稳定,故对其进行全面分析很有必要。     

浅谈活性氧化铝对双氧水生产的影响

活性氧化铝在蒽醌法双氧水生产工艺中,主要作用是吸附工作液中夹带的碱以及再生工作液在氢化,氧化反应过程中因副反应产生的副产的,在双氧水生产过程中,怎样选择和用好活性氧化铝,对双氧水的产量和质量极为重要。     

干式稀油密封煤气柜密封油聚结-真空联合脱水工艺探讨

对煤气柜密封油进行聚结分离脱水、真空分离脱水、聚结-真空串联和聚结-真空并联的联合脱水。结果表明,相较于单纯的聚结分离脱水和真空分离脱水,密封油聚结-真空联合脱水具有较为明显的优势;相较于聚结-真空串联工艺,聚结-真空并联工艺可根据密封油工况调节聚结分离和真空分离的联合方式,在脱水效率、能耗方面的优势较为明显。     

超临界CO_2萃取干燥技术及其在饱水文物脱水中的研究进展

饱水文物的脱水干燥是文物保护领域中一个重要的环节,直接关系到饱水文物的存在与否及其品相的高低。超临界CO2萃取干燥技术利用CO2气体在临界温度以上,控制饱水文物内部液体在临界点之上,使气/液界面消失,在无液相表面张力情况下进行的干燥过程。与传统脱水技术相比,超临界CO2萃取干燥技术具有处理周期短、脱水效率高、干燥应力小、脱水过程同时对文物杀菌和清洗等优点。综述了超临界CO2萃取干燥技术及原理、萃取干燥工艺流程,对国内外应用该技术对饱水文物脱水研究进行了简要评述,并展望了其发展趋势。     

干式稀油密封煤气柜密封油聚结-真空联合脱水工艺探讨

对煤气柜密封油进行聚结分离脱水、真空分离脱水、聚结-真空串联和聚结-真空并联的联合脱水。结果表明,相较于单纯的聚结分离脱水和真空分离脱水,密封油聚结-真空联合脱水具有较为明显的优势;相较于聚结-真空串联工艺,聚结-真空并联工艺可根据密封油工况调节聚结分离和真空分离的联合方式,在脱水效率、能耗方面的优势较为明显。     

双氧水生产原料“工作液”的选择和再生处理

介绍国内外双氧水工业生产中工作液的选择标准和进展，指出工作液在双氧水生产中的重要性及再生处理。     

浅谈蒽醌法生产双氧水影响氢化工艺的几个因数

介绍了蒽醌法生产双氧水工艺中氢化的工艺条件,指出了氢气分压和纯度、氢化温度、氢化液循环、工作液中水分含量、工作液中过氧化氢含量和循环工作液碱度对氢化工艺的影响,并给出了最佳设计参数。     

用Aspen Adsorption模拟氯化氢脱水

利用Aspen Adsorption模拟氯化氢吸附脱微量水过程。通过吸附平衡试验数据估算吸附等温线的常数项,用简化的单塔模型进行了穿透曲线的模拟,得到吸附塔内空隙中水的浓度分布以及塔内吸附剂的吸附量随时间的变化情况,可以看到传质区在轴方向上移动;进一步研究了传质系数和操作压力的变化对穿透曲线的影响,变化趋势与文献报道一致。     

高含水率中药渣的带式压滤机压滤脱水试验

分析中药渣中的水分,阐述中药渣受挤压作用时的脱水机理,结合中药渣的特性和带式压滤机的脱水工艺,对压滤机的布料器进行改造,增加两级分料螺旋,改善压滤效果,使其适用于中药渣脱水试验,增加物料处理量,减少溢料现象,降低污水含固率,减少运行人员劳动强度。采用控制变量法,试验研究压滤机的不同脱水段、压力、带速、中药渣初始含水率等4个因素对脱水效果的影响,结果表明：物料初始含水率越大,不同脱水段的脱水率越大,滤饼的含水率越大;Ⅰ级脱水辊对物料脱水效果影响最大,楔形预压段对物料脱水效果影响最小;中药渣的初始含水率不宜超过80.16%;Ⅰ级脱水辊压力选择0.2～0.6MPa较合适;带速在0.3～0.5m/s范围内时,滤饼的含水率在65%～ 66%之间,脱水效果较好。     

Dehydration of potato slices following brief dipping in osmotic solutions: Effect of conditions and understanding the mechanism of water loss

A novel variant of osmotic dehydration, named here as postdipping dehydration—where a material is dipped in a salt or sugar solution for a very short time followed by simple exposure to ambient conditions was explored with the aim of lowering water content of potato slices but at the same time not gain a high level of sugar/salt. The rate of water loss, which was rapid initially, was found to approach equilibrium. This article also explored whether the water loss process could subsequently be kick started once again, by employing a multistage process, where each stage consisted of osmotic solution dipping followed by ambient holding of the potato slices that had reached equilibrium in the earlier stage. Water loss values comparable to conventional osmotic dehydration could be achieved thus, but with significantly lower overall solid gain (<50%)—which can potentially yield a significantly healthy product option.     

Pulsed Electric Field Pretreatment for Osmotic Dehydration of Apple Tissue: Experimental and Mathematical Modeling Studies

The aim of this study was to analyze the influence of pulsed electric field pretreatment (PEF) on the osmotic dehydration of apple tissue. Osmotic dehydration was carried out in sucrose solution at 40°C and 100 rpm in a water-bath shaker. PEF pretreatment was performed using varying field strength of 5 and 10 kV/cm and 10 and 50 pulses. On the basis of electric conductivity measurement, the cell disintegration index was calculated. The course of osmotic dehydration was described by means of water loss, solid gain, weight reduction, and water content changes. Moreover, the course of the process was described by different mathematical models that are commonly used in the literature. PEF application before osmotic dehydration significantly increased water loss after 60 minutes of the process. In turn, no significant differences were found in the case of solid gain. The highest osmotic dehydration efficiency ratio (WL/SG) was noticed for samples treated by PEF at the electric field strength of 5 kV/cm and 10 pulses. The statistical analysis of mathematical modeling of the process showed the equations utilized generally exhibit a good fit to the experimental data.     

气体搅拌萃取过氧化氢实验研究

在内径为50 mm的筛板塔内,研究了空气-水-蒽醌工作液三相体系萃取过氧化氢过程.萃取温度为40℃,空气和分散相的表观流速分别为(1.31～3.22)×10-3m·s-1和(1.27～1.70)×10-3 m·s-1,分散相和连续相的表观流速之比为50:1.结果表明,在普通液-液萃取过氧化氢过程中引入气体作搅拌,可减小分散相的液滴直径,增大相际接触面积,明显提高萃取效率,降低萃余相中过氧化氢的含量.传质单元高度随气体表观流速的增加而降低,传质系数随气体表观流速的增加而增大.     

煤层气脱水工艺分析

对国内AW煤层气进行三甘醇法(TEG)脱水工艺模拟分析,可以得出:随着原料煤层气压力增大,脱水率增大,水露点降低,但变化的幅度均逐渐减小;原料气温度则相反,温度升高时,水露点升高和脱水率降低,变化幅度逐渐增大;进料量增大时出现"吹液"而使得脱水效果降低;随贫液温度升高,水露点和脱水率分别呈线性增大和减小,但总体上影响不大;综合考虑制造成本和脱水效果,存在一个最优塔板数,若在此基础上继续提高塔板数意义不大。     

采用新型吸附剂及变温变压吸附技术脱除氯乙烯单体中的水分

介绍了采用新型吸附剂及变温变压吸附技术脱除氯乙烯单体中水分的原理及工艺流程。该技术用于20万t/a氯乙烯单体装置的深度脱水处理后,氯乙烯单体的含水质量分数由700μg/g下降到20~50μg/g。该技术脱水能力强、效率高,生产过程中无"三废"排放。     

Effects of pretreatments on properties of microwave-vacuum drying of sweet potato slices

Abstract

Pretreatments of blanching (BL); osmotic dehydration at 35°Brix of sucrose (OD); ultrasound in distilled water (UD), and ultrasound-assisted osmotic dehydration (UO) were carried out for microwave-vacuum drying (MVD) orange- and purple-flesh sweet potato slices, and effects on their properties were investigated in this study. UO had improvements effects on water loss, solid gain, and relaxation time of the samples compared to other pretreatments. Low-field nuclear magnetic resonance results offered a view of water state concerning the effects of different pretreatments on sweet potato. UD treatment following by BL showed a long relaxation time corresponding to the weaker degree of bound hydrogen proton or the greater freedom degree of hydrogen comparing to other pretreated samples. Differential scanning calorimetry parameters appeared to be sensitive to pretreatments by increased Tg value compared to blanched sample. The value of Tg shows that it does not depend only of the water content but also on the experimental conditions (pretreatments). The dried sweet potato exhibited amorphous structures as evidenced by the X-ray diffractograms due to the BL treatment and MVD. Concentration of total phenolics and anthocyanins were high in purple sweet potatoes, whereas content of vitamin C and total carotenoid were high in orange ones. Application of UO is suitable for retention of bioactive compound and stability of MVD sweet potato slices.     

Effect of Various Pretreatments on the Quality of Vacuum-Fried Carrot Chips

Carrot slices were subjected to the following four different pretreatments prior to vacuum frying: (1) blanching, (2) blanching and air drying, (3) blanching and osmotic dehydration, (4) blanching, osmotic dehydration, followed by freezing. The effects of these pretreatments on the physicochemical properties and fat distribution in vacuum-fried carrot chips were also investigated. There were significant differences in the total yield, amounts of carotenes, vitamin C, and the color values of carrot chips following different pretreatments (P < 0.05). Pretreatment significantly affected the water content, fat content, and water activity of carrot chips (P < 0.05), while there were no significant differences in the breaking force of carrot chips treated with different pretreatments (P > 0.05). Spearman correlation analysis showed a high positive correlation between the fat content of carrot chips and the initial water content of carrot slices. The fat distribution pattern depended on the initial water content and the structure of the material left by water evaporation.