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不同类型载气对乙醇气提发酵的影响 总被引:2,自引:0,他引:2
研究了在乙醇气提发酵过程中,分别使用空气、二氧化碳、氮气和高纯氮作为气提载气对细胞生理及乙醇发酵的影响. 结果表明,空气能维持细胞生长和活力,但发酵效果最差,二氧化碳使细胞发酵能力波动不稳定且抑制副产物甘油合成;而以浓度为99.5%~99.8%的氮气为气提载气取得了较好的效果,乙醇和甘油的生产速率比不气提批式发酵分别提高2倍和1.9倍. 对以高纯氮(99.999%)为气提载气的研究发现,发酵进行到47 h开始出现菌种大量死亡现象,此时适当通氧和补充生长所需营养物质,细胞数量回升,活性恢复,最终乙醇生产速率比不气提时提高1.3倍. 相似文献
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同时进行发酵和分离的CO2气提、活性碳吸附乙醇发酵动力学研究(二)游离细 总被引:3,自引:0,他引:3
本文研究了游离细胞连续发酵时应用CO2气提、活性炭吸附的乙醇发酵和分离动力学,考察了稀释率和进口葡萄糖浓度对发酵速率的影响,提出了包括CO2汽提乙醇速率的发酵动力学模型,研究了连续发酵时的稳态和动态过程,结果表明,CO2气提有助于减少乙醇对酵母的抑制作用,发酵动力学模型可以较好地关联稳态时的发酵动力学数据,从中获得的模型参数可以用于预测动态过程中底物,微生物及产物的变化规律。对于所研究的过程,存在着最佳稀释率和进口糖浓度以获得最大发酵速率。 相似文献
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本文研究了游离细胞连续发酵时应用 CO_2气提、活性炭吸附的乙醇发酵和分离动力学,考察了稀释率和进口葡萄糖浓度对发酵速率的影响,提出了包括 CO_2汽提乙醇速率的发酵动力学模型,研究了连续发酵时的稳态和动态过程,结果表明,CO_2气提有助于减少乙醇对酵母的抑制作用,发酵动力学模型可以较好地关联稳态时的发酵动力学数据,从中获得的模型参数可以用于预测动态过程中底物、微生物及产物的变化规律。对于所研究的过程,存在着最佳稀释率和进口糖浓度以获得最大发酵速率。 相似文献
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玉米发酵总溶剂的蒸馏节能技术改造牛文晋蒸馏过程是一个化工过程。总溶剂的蒸馏是一个多元混合物的蒸馏。由于发酵醪中仅含有1.8~2.0%的混合溶剂,95%以上均是水,还有少量的固形物,因此,总溶剂蒸馏的目的是要将发酵醪中少量的丙酮、丁醇、乙醇等产品蒸出来... 相似文献
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发酵与分离技术结合的过程及其在乙醇生产中的应用 总被引:2,自引:1,他引:2
本文系统地介绍了超滤、溶剂萃取、膜蒸馏、超滤及反渗透、渗透蒸发和渗透牵引等分离技术与发酵过程结合的基本原理,重点介绍了这些技术在乙醇发酵中的应用及新进展。与分离技术结合的乙醇发酵过程的开发,为提高生产率、降低生产成本开辟了一条新途径,是一种很有应用前景的乙醇生产方法。 相似文献
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Ethanol is a biofuel, produced through the fermentation of sugars derived from biomass. Its usefulness as a fuel is limited by the energy intensive nature of the ethanol separation process. The ethanol recovery process is inefficient due to the dilute nature of the fermentation product and the presence of the ethanol?water azeotrope. This investigation presents a new hybrid separation process for energy efficient ethanol recovery. The new process is a hybrid of distillation and pervaporation. However, as opposed to most other hybrid processes, the distillation and pervaporation processes are combined into single unit. An overview of the proposed system was provided and differences to the conventional separation process were highlighted. A mathematical model was derived to explain the transport phenomena occurring in the hybrid process. The model was then used to compare the process to distillation. It was shown that the hybrid process is capable of breaking the ethanol-water azeotrope. It was also demonstrated that the pervaporation process, which is associated with both material and energy transfer, induces partial condensation of the vapor and thereby affects the efficiency of vapor?liquid contacting. Simulations were presented to show the impact of reflux ratio and pervaporation flux on the performance of the process. 相似文献
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为提高乙醇生产发酵强度,提出了同步汽提闪蒸乙醇发酵新过程。该过程集合了闪蒸发酵和汽提发酵的优点,在发酵的同时能更有效地在位分离乙醇,从而提高发酵强度。通过与普通发酵、闪蒸发酵、汽提发酵等过程进行间歇实验比较,同步闪蒸汽提发酵过程具有发酵强度高的优势;而且,采用耐高温酵母高温发酵、提高通气量、闪蒸罐的进料流速可进一步提高其发酵强度。该过程简单、高效,具有工业应用的潜力。 相似文献
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Liu Mo Jiang Shao-Tong Pan Li-Jun Zheng Zhi Luo Shui-Zhong 《Chemical Engineering Research and Design》2011,89(11):2199-2206
Esterification of raw lactic acid from fermentation broth and then hydrolysis of lactate ester in reactive distillation column is an effective process for purification of lactic acid. Reactive distillation for hydrolysis of methyl lactate is studied. First, the thermodynamic properties and reaction kinetics are analyzed; then the reactive distillation column is designed based on the objective function total annual cost. The effects of tray number of rectifying section, tray number of reactive section, and feed location on the total annual cost are investigated. And a dual-temperature control structure is proposed for the optimal reactive distillation column, and the results show that it works quite well for this hydrolysis system. 相似文献
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In this article, we address the conceptual design of the bioethanol process from switchgrass via gasification. A superstructure is postulated for optimizing energy use that embeds direct or indirect gasification, followed by steam reforming or partial oxidation. Next, the gas composition is adjusted with membrane‐PSA or water gas shift. Membrane separation, absorption with ethanol‐amines and PSA are considered for the removal of sour gases. Finally, two synthetic paths are considered, high alcohols catalytic process with two possible distillation sequences, and syngas fermentation with distillation, corn grits, molecular sieves and pervaporation as alternative dehydration processes. The optimization of the superstructure is formulated as an mixed‐integer nonlinear programming problem using short‐cut models, and solved through a special decomposition scheme that is followed by heat integration. The optimal process consists of direct gasification followed by steam reforming, removal of the excess of hydrogen and catalytic synthesis, yielding a potential operating cost of $0.41/gal. © 2011 American Institute of Chemical Engineers AIChE J, 2011 相似文献
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针对催化蒸馏法干气制乙苯过程,建立非平衡级模型,并进行了计算机模拟.结果表明,非平衡级模型可用于模拟催化蒸馏法干气制乙苯过程,模拟结果与试验值吻合较好.以模拟结果为依据,考察了各工艺条件的影响,并提出了催化蒸馏法干气制乙苯过程适宜的工艺条件. 相似文献
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The separation of NGL (natural gas liquids) in gas processing is energy-intensive, requiring systematic process design and optimization to reduce energy consumption and to identify cost-effective solutions for the recovery valuable hydrocarbons. As NGL fractionation processes require a sequence of distillation columns to separate multi-component mixtures the determination of optimal energy-efficient distillation sequences and operating conditions is not a simple task. A design methodology is proposed in this study in which the process simulator Aspen HYSYS® is linked with an optimization algorithm available in MATLAB®. The proposed methodology involves a procedure where in the first step possible distillation sequences are screened using a short-cut distillation column model. In the second step a few selected and promising candidate distillation sequences are further simulated and optimized, again using the same short-cut model. Finally, rigorous simulations are used to validate and confirm the feasibility of the optimal designs. A case study is presented to demonstrate the applicability of the proposed design framework for the design and optimization of NGL fractionation processes in practice. 相似文献
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《分离科学与技术》2012,47(10):1518-1528
One of the main challenges when a biochemical conversion technique is employed to produce cellulosic ethanol is the low concentration of ethanol in the fermentation broth, which increases the energy demand for recovering and purifying ethanol to fuel grade. In this study, two design cases implementing salt extractive distillation—with salt recovery enabled by a novel scheme of electrodialysis and spray drying—along with heat integrated distillation techniques of double-effect distillation and direct vapor recompression are investigated through process simulation with Aspen Plus® 2006.5 for reducing the thermal energy demand. Conventional distillation along with molecular sieve based dehydration is considered as the base case. Salt extractive distillation along with direct vapor recompression is found to be the most economical ethanol recovery approach for cellulosic ethanol with a thermal energy demand of 7.1 MJ/L (natural gas energy equivalents, higher heating value), which corresponds to a thermal energy savings of 23% and cost savings of 12% relative to the base case separation train thermal energy demand and total annual cost. 相似文献
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高纯度酒精广泛应用于食品、医药和石油化工等行业,国内外制备高纯度酒精的常用方法为酒精五塔精馏,但传统酒精精馏工艺往往伴随高能耗与高成本。为了解决上述问题,本文提出一种精馏-吸附-膜分离耦合新工艺,从乙醇发酵液中高效获得高纯度酒精。借助Aspen Plus流程模拟软件对精馏-吸附-膜分离耦合工艺进行研究,并用灵敏度分析工具对其精馏塔部分进行参数优化。结果表明,当精馏塔的塔板数为37、回流比为9、进料位置为第35块塔板、吸附剂采用天然沸石、膜分离用聚偏氟乙烯渗透汽化膜时,乙醇质量分数达到99.2%,乙醇回收率为65.6%。与传统五塔精馏方法相比不仅能获得高纯度酒精,而且能耗与设备成本相对较低,也充分提高了空间利用率,具有很好的工业前景。 相似文献