Factors affecting ice crystal purity during freeze concentration process for urine treatment

Freeze concentration has great potential in treating wastewaters containing soluble pollutions. It is important for freeze concentration process to produce ice crystals with large size and high purity. In this work raw urines of 4660 -7914 mg/L in COD, 512. 71 -872. 41 mg/L in NH3 -N and 22600 -28800 μs/cm in electric conductivity were studied. Urines were frozen by a digital refrigerated circulator bath. Ice crystals were purified by ice-water steep and vacuum filtration. The COD, NH3 - N, and electric conductivity levels of the melted ices were measured to reflect ice crystal purity. Effects of coolant temperature, ice crystal shape, initial solution temperature, solution concentration, ice seeding, re-crystallization process and crystallization time on ice crystal purity were analyzed. The results show that an appropriate coolant temperature, suspended ice crystals, an initial solution temperature of about 6 ℃, introduction of seed ice, addition of re-crystallization process, and crystallization time of less than 30 min axe in favor of producing ice crystals with high purity. Under such conditions, more than 99 percent of inorganic salts, COD and NH3 - N sources in raw urine could he removed.

Freeze Concentration of Proteins in Antarctic Krill Wash Water

Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen(FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.

Modelling of heat transfer for progressive freeze concentration process by spiral finned crystallizer

This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.

Process Optimization of Effective Partition Constant in Progressive Freeze Concentration of Wastewater

Response surface methodology (RSM) was employed to optimize the process parameters for effective partition constant (K) in progressive freeze concentration (PFC) of wastewater. The effects of coolant temperature, circulation flowrate, initial solution concentration and circulation time on the effective partition constant were observed. Results show that the data were adequately fitted into a second-order polynomial model. The linear and quadratic of independent variables, coolant temperature, circulation flowrate, initial solution concentration and circulation time as well as their interactions have significant effects on the effective partition constant. It was predicted that the optimum process parameters within the experimental ranges for the best K would be with coolant temperature of -8.8℃, circulation flowrate of 1051.1 ml/min, initial solution concentration of 6.59 mg/ml and circulation time of 13.9 minutes. Under these conditions, the effective partition constant is predicted to be 0.17.

The Impact of the Block Freeze Concentration Process on Human Milk Properties Intended for Feeding Newborns

Human milk is the ideal nutritional support for premature neonates. Considering the need for aggregating nutritional value to human milk provided to such vulnerable group of infants, human milk was concentrated by the block freeze concentration technique. The effects of freeze concentration on the physicochemical properties, the efficiency of the process, color parameters, and the density and dynamic viscosity of human milk were assessed. The freeze concentration technology was used to successfully concentrate human milk to a factor equal to 180.48% and 72% of total solid retention in the second stage of freeze concentration. The values observed in the concentrates for the biochemical properties showed that the fraction of concentrated fluid human milk of the second stage (C2) presented elevated amounts of carbohydrates, protein and energy. The elevated caloric value observed in the ice fraction of the first stage (I1) refers to the retention of lipids in it. When added to human milk, C2 and I1 may satisfy the special requisites of nutrients and energy to guarantee the growth and development of preterm neonates.

Experimental Study of Mineral Salts Concentration in Seawater

Mineral salts are of great importance on the regulation of different metabolic activities of living organisms. The well-functioning of the body depends on mineral salts. These salts, existing naturally in small quantity in our diverse diets （grains, legumes, fruit, tea, egg, etc.）, are concentrated in seawater. In this paper, the indirect fi＇eezing is used as a concentration process to recover the most of salt minerals naturally present in seawater. Freezing is known as a purification process, but this paper recovers the brine instead of the formed ice. A 3.5% salinity solution with an appropriate setup is used to recover the maximum of salt in the brine. The work aims to develop a process for freezing salt concentration on cold walls. The influence of operating parameters has highlighted the important role of the cooling ramp and stay time on the salt concentration produced.

冻融循环对食用菌预制菌汤品质的影响

为探究冻融循环对食用菌预制菌汤的品质影响,本文以鲜菌汤为参照,对比了冻融过程中微生物数量、菌汤色泽、可溶性蛋白、还原糖、总酚含量等基本指标的变化,并基于超高效液相检测和气相色谱-质谱法分析冻融过程菌汤等鲜度和挥发性风味物质差异。研究表明,首次冻融大幅减少了菌汤的还原糖、总酚和总氨基酸含量,显著降低了菌汤等鲜度和挥发性成分含量,综合影响了菌汤的成分与风味。进一步通过冻融次数(1~5次)之间的对比,反复冻融3次菌汤可溶性蛋白含量相较于冻融1~2次显著降低(P<0.05),此外,等鲜度由1~2次冻融的0.441~0.450 g MSG/100 g直接下降至0.407 g MSG/100 g,同时微生物开始检出。在此后4~5次冻融过程中,虽然菌汤总酚、总氨基酸含量和等鲜度相对稳定,但核苷酸、可溶性蛋白和挥发性成分不断减少且菌落总数不断升高。因此,预制菌汤若需冻融处理则应控制在2次内为宜。

奥扎格雷氨丁三醇注射用浓溶液使用中及低温冻融稳定性研究

目的 考察奥扎格雷氨丁三醇注射用浓溶液使用中及低温、冻融稳定性,为其临床使用、贮藏和运输提供参考。方法 奥扎格雷氨丁三醇注射用浓溶液分别采用0.9%氯化钠注射液和5%葡萄糖注射液稀释,于0,2,4,6,8和24 h检测配伍后溶液的性状、pH、有关物质、不溶性微粒、可见异物及含量;奥扎格雷氨丁三醇注射用浓溶液分别经低温(2~8℃)和冻融(-10~-20℃)各3个循环,考察性状、pH、有关物质、不溶性微粒、可见异物及含量的变化。结果 奥扎格雷氨丁三醇注射用浓溶液分别用0.9%氯化钠注射液与5%葡萄糖注射液稀释后,24 h内各项检测指标均符合规定,且与0时相比无明显变化;奥扎格雷氨丁三醇注射用浓溶液经历低温、冻融各3个循环,各检测指标也均符合规定,且与0时相比无明显变化。结论 奥扎格雷氨丁三醇注射用浓溶液与0.9%氯化钠注射液、5%葡萄糖注射液在24 h内配伍稳定性良好;短期内经历低温或冷冻条件,不影响奥扎格雷氨丁三醇注射用浓溶液的质量。

经典名方黄芪桂枝五物汤不同形态基准物质质量评价及分析

目的建立经典名方黄芪桂枝五物汤(Huangqi Guizhi Wuwu Decoction,HGWD)物质基准;研究HGWD饮片-水煎液-浓缩液-冻干粉全过程量值传递规律,为含挥发性物质的经典名方基准样品的制备方法和科学评定提供借鉴。方法根据国家发布的《古代经典名方关键信息表(25首方剂)》制备15批HGWD水煎液;建立其多指标含量测定和特征图谱分析方法,开展特征峰归属及相似度评价;考察比较HGWD水煎液、冻干粉中多指标含量,分析其在水煎液-浓缩液-冻干粉制备过程中量值传递规律,科学合理确定基准样品的物理形态,并拟定HGWD基准样品中各成分的含量和转移率范围,建立HGWD物质基准。结果HGWD中桂皮醛、肉桂醇在浓缩干燥过程中显著降低,其余指标成分在水煎液、浓缩液与冻干粉间能较完整地传递;15批HGWD基准样品的特征图谱相似度均>0.9,确定8个特征峰,分别来自于方中白芍、桂枝和生姜;出膏率范围8.0%~11.0%;指标成分黄芪甲苷含量为0.04%~0.07%,转移率为9.0%~18.0%;芍药苷含量为1.5%~3.0%,转移率为33.0%~62.0%;肉桂醇含量为0.02%~0.04%,转移率为25.0%~47.0%;桂皮醛含量为0.02%~0.05%,转移率为0.7%~1.5%;肉桂酸含量为0.03%~0.06%,转移率为17.5%~34.0%;6-姜辣素含量为0.04%~0.08%,转移率为7.0%~14.0%。结论确定以水煎液作为HGWD基准样品物理形态,为含挥发性物质的经典名方基准样品物理形态的科学选择提供参考;建立了HGWD物质基准各项质量指标,并对其量值传递规律进行分析,为该经典名方复方制剂开发提供依据。

酶法头孢拉定母液冷冻浓缩提取工艺研究

以头孢拉定离心母液为研究对象,研究了冷冻浓缩提取头孢拉定工艺,考察了冷冻装置、冷冻温度、pH、冷冻时间及搅拌方式等因素对冷冻浓缩效果的影响。结果表明:采用内刮式冷冻浓缩装置进行冷冻浓缩,冷冻温度-8℃,冷冻时间4 h,搅拌转速150 r/min时,冷冻浓缩效果较好,头孢拉定提取率88.7%。

CR200J型动力集中动车组气路控制箱结冰问题分析及改进

为满足广大乘客在舒适性、经济性、安全性等方面的需求,中国铁路乌鲁木齐局集团有限公司配属了时速160 km“复兴号”CR200J型动力集中动车组。冬季动力集中动车组途经高寒、暴雪、大湿度的运行区段,沿线历年极端低温为-40~-30℃,北疆的精伊霍线、奎北线相对湿度为50%~80%;出现了多起动力集中动车组拖车气路控制箱结冰的问题,造成了塞拉门、集便器、空气弹簧无风等严重故障。文章从动力集中动车组运用环境、干燥器控制逻辑、供风管路、运用维修等方面进行分析,得出了冬季北疆运行线路低温、大湿度是气路控制箱结冰的外部原因,干燥器启停与空压机打风不同步、拖车供风管点取在总风缸Ⅰ之前是气路控制箱结冰的内部原因。通过优化干燥器控制逻辑、优化供风管路、调整运行交路、优化冬季排水作业、增加干燥器检查等改进措施,后续未发生气路控制箱结冰造成塞拉门、集便器、空气弹簧无风的故障,提高了乘客乘坐安全性和舒适性,确保了动力集中动车组的运营安全。

响应面法优化冷冻浓缩处理高盐染料化工废水研究

采用渐进冷冻浓缩法处理染料化工废水,在单因素试验的基础上,依据响应面分析法(RSM)的中心组合设计(BBD)原理,探究了冷却剂温度、搅拌速率和冷冻时间对盐和COD去除率的交互作用,并建立了多元线性回归预测模型。结果表明:在模型分析最佳试验条件(冷却剂温度为-7.7℃,搅拌速率为320 r/min,冷冻时间为55 min)下,盐和COD去除率的预测值分别为72.24%和72.18%。在上述最佳条件下试验测得的盐和COD去除率分别为70.40%和69.90%,与模型预测值的相对偏差均在5%以内,验证了回归模型的准确性和实用性。

氯离子对盐渍化寒区路基填土盐胀的影响研究

盐渍化寒区路基填土通常为富含氯化钠和硫酸钠的复合盐渍土。为探究氯离子含量对盐渍化寒区路基盐胀的影响机制,基于Pitzer离子模型中氯化钠-硫酸钠-水三元体系溶液计算理论,结合FREZCHEM模型,定量分析水分活度、成冰因子和过饱和比与温度、浓度比(η=m_(Cl^(-))/m_(SO_(4)^(2-)))的内在关联,研究了复合盐渍土的冻结温度和结晶过饱和比随硫酸钠含量、浓度比的变化规律,揭示了氯化钠对硫酸盐渍土结晶的影响机制,确定了硫酸盐渍土中添加氯化钠降低盐胀的临界浓度比。研究结果表明:FREZCHEM模型可用于分析复合盐渍土的冻结和盐分结晶特性,成冰因子与温度和溶液浓度密切相关,当其等于1时,孔隙溶液处于热力学平衡状态;氯化钠对硫酸钠结晶析出具有促进或抑制双重作用,当盐渍土中硫酸钠的浓度大于1.0 mol/kg时,按照临界浓度比大于2.5添加氯化钠,会显著降低硫酸盐渍土的盐胀变形。同时,现场施工中采用盐化法可有效抑制盐渍化寒区路基的盐胀变形。

基于不同方案比选的煤化工高盐废水处理技术

煤化工废水处理面临着成本与环境影响的双重挑战,尤其对于高浓度氯化钠废水的处理极具挑战性。针对这一问题,研究采用了结合悬浮冷冻浓缩与低温溶析结晶的技术方案,旨在提高氯化钠的回收率。并系统性地探讨了冷冻温度、搅拌时间及NaCl初始浓度对NaCl回收效果的影响。实验结果显示:在-10℃的悬浮冷冻温度下,浓缩液浓度与冰晶纯度获得了最佳表现。在搅拌时间为60 min、NaCl浓度为25.0%的条件下,NaCl的回收率最高,可达38.68%。该方法为废水中无机盐类的再回收利用提供了新的途径,对煤化工废水处理技术的进步具有实际和理论上的推动作用。

Comparison of high-energy multi-pass Ti:sapphire amplifiers with a different Ti-dopant concentration

We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic lasing（PL）and transverse amplified spontaneous emission（TASE）, the self-phase-modulation（SPM） effect becomes more pronounced when a longer crystal is used. Recompression of the amplified, stretched pulses can be seriously affected by the SPM effect. We then propose a temporal multi-pulse pump scheme to suppress PL and TASE in a thin, heavily doped Ti：S crystal. This novel temporal multi-pulse pump technique can find potential applications in 10 PW chirped-pulse amplification laser systems.

橙汁冷冻浓缩动力学模型的研究

为了降低果汁在冷冻浓缩过程中由于冰晶夹带造成的的损失并提高浓缩速度,需要获得冷冻浓缩过程中冰晶的增长规律。以橙汁为原料,采用二级冷冻浓缩方法,利用冰与水溶液之间的固液相平衡的原理,将水分从液态转变为固态的冰,使橙汁的浓度从13°Bx浓缩到34°Bx。该试验中,测定了橙汁的浓度及其对应的冻结点温度的关系,结果表明:在试验范围内,冻结点与浓度呈线性关系并随浓度的升高而降低。该文还研究了在冰晶中所夹带的可溶性固形物与橙汁浓度的关系,所获得分配系数K表明,冰晶中所夹带的可溶性固形物随浓度的提高而增加。根据Fick扩散方程式建立了冰晶增长动力学模型,模型显示冰晶增长速率与冰晶质量成正比,同时也受到最大冰晶量的抑制,采用Powell法,对试验数据回归模型参数、采用龙格—库塔法进行数值积分求得模型解,计算结果与试验结果吻合,该模型有助于为建立冰晶增长的质量、热量传递之间的平衡提供一定的理论依据和试验参考,加深对橙汁冷冻浓缩过程的认识。

冷冻浓缩法处理大豆乳清废水的研究初探

应用冷冻浓缩的方法处理大豆乳清废水。实验结果表明,经过冷冻处理后的大豆乳清废水,可以较大地降低其COD值,又可以使乳清废水中乳清蛋白、大豆低聚糖及大豆异酮的最高浓缩倍数分别达到乳清原液浓度的2.737、3.858和3.120倍。

基于相场法的液态食品冷冻浓缩冰晶生长数值模拟

旨在建立冷冻浓缩过程冰晶生长的数理模型,用以微观上分析冰晶夹带造成液态食品中溶质损失的问题。探讨结晶时间对冰晶形貌的影响。采用国内外描述相变微观结构的相场模型,将液态食品体系视为水和溶质二元结构,模拟冰晶生长的演变过程。研究等温结晶情况下,计算时间对冰晶生长形貌的影响及其对冰晶内部溶质浓度分布的影响。模拟结果表明,随着时间的延长,冰晶形貌逐渐变大,主干变细,二次分枝乃至三次分枝更加发达;同时,冰晶所包含的溶质浓度越大,各区域的溶质浓度分布也随之改变。由于溶质再分配,冰晶溶质分布曲线存在着波峰与波谷,波峰对应着来不及扩散溶质的冰晶尖端,波谷对应着冰晶固相。结果启示,在等温情况适当控制结晶时间将有效控制冷冻浓缩过程冰晶的形貌演化,降低液态食品冷冻浓缩过程的溶质损失。为进一步研究各种因素对冰晶生长的影响提供理论依据,从而为改进冷冻浓缩工艺、推进其工业化提供技术支持。

冰冻浓缩对低糖葡萄汁及葡萄酒品质的影响

冰冻浓缩是一种可以较好地保持葡萄汁的品质、香气和营养成分的浓缩方法。经过冰冻浓缩折光度提高5°Brix的玫瑰蜜葡萄汁含糖量提高了53．8g/L,可滴定酸含量增加接近1倍,但果汁的pH值变化不明显。冰冻浓缩的葡萄汁和加糖处理的葡萄汁相比,前者保持了发酵起始快、发酵强度高的特点,后者出现明显的起始延迟和后期发酵结束延迟的现象。与果汁直接添加蔗糖相比,冷冻浓缩果汁发酵后成酒色泽、香气、口感与酒体结构等感官品质显著改善。

泡菜活性直投式乳酸菌发酵剂的研究

本试验以MRS为培养基,对5株乳酸菌进行了生长性能和发酵性能研究。优选其中两株菌作为制备发酵剂的菌种,前期研究高密度细胞培养的条件、培养基成分,以培养过程中的pH值、活菌数为指标,后期研究制备发酵剂的最佳离心条件、筛选最适的冻干保护剂及浓度等进行了系统研究,研究表明,在接种量2%,培养温度30℃,初始pH6.6,装液量40ml(100ml三角瓶),振荡频率120r/min条件下培养,培养14h后补充营养物质继续培养,到20h时可使乳酸菌活菌数达到7.24×109CFU/ml。4℃、4000r/min离心30min为收集细胞的最佳条件,以10%的脱脂乳为冻干悬浮基质,对蔗糖、血清蛋白、甘油、海藻酸钠四种保护剂的保护效果进行了研究,结果表明,甘油的保护效果最佳,冻干后菌体的存活率最高,但甘油的吸湿强,给真空冷冻干燥后的活性菌种的分装带来困难,综合考虑选用10%的脱脂乳和血清蛋白作为冷冻保护剂。该研究旨在为直投式的乳酸菌发酵剂工业化生产提供理论依据。