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缩放型导流筒气升式内环流生物反应器流体力学与传质特性 总被引:15,自引:0,他引:15
从气相含率、液体循环速度和体积氧传质系数方面研究缩放型导流筒气升式内环流生物反应器内的流体力学与传质特性。实验结果表明,与传统圆柱形导流筒相比较,缩放型导流筒气相含率和体积氧传质系数分别提高8%和10%以上。气相含率和体积氧传质系数随固含率的增加而提高,液体循环速度随固含率的增加而减小;同一内管反应器随介质粘度的增加,体积氧传质系数减小。此外还在Higbie穿透理论和Kolomogoroff各向同 相似文献
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微量醇及电解质强化气液传质的研究 总被引:1,自引:0,他引:1
在气升式内环流反应器中考察了微量醇类物质(乙醇、叔丁醇、季戊四醇)及电解质(CaCl2)对氧的液相体积传质系数和气含率的影响。结果表明,向空气-水体系中添加微量醇类物质可以明显改善气液传质性能,同时醇类物质强化气-液传质存在一极限浓度,超过此浓度后,氧的液相体积传质系数略有降低;当表观气速增加时,去离子水体系和含醇体系的气含率都增加,但醇体系的气含率明显高于去离子水体系。此外,添加电解质CaCl2也会使氧的液相体积传质系数有所提高,并从离子强度的角度对其抑制气泡聚并的机理进行了分析。 相似文献
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对一种自吸式反应器的气液分散性能进行了实验研究,并采用计算流体力学(CFD)ANSYS CFX中对自吸式反应器在600,800,1 000,1 200 r/min 4种转速条件下气液二相流的流场、局部气含率及整体气含率进行了数值模拟,并采用Higbie溶质渗透模型模拟研究了反应器的容积传质系数。研究结果表明:气液二相流场与高速摄像机拍摄的结果相同,成对称分布;自吸式反应器的局部气含率分布均匀,上下分布良好,整体气含率的模拟结果与实验结果一致,实验值和模拟值误差为5.1%;局部容积传质系数分布良好,气体出口附近较好,容积传质系数模拟值与实验值变化趋势一致。 相似文献
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气升式环流反应器强制振荡周期对传质影响的研究 总被引:2,自引:0,他引:2
在同一反应器中比较了不同振荡周期下的气液传质特性,为最优强制振荡周期的确定提供了实验依据和分析基础。选择体积传质系数及气含率作为传质研究的主要评价指标,实验结果表明,动态操作下的传质效果明显优于稳态,而不同振荡周期传质效果也大不一样。在0.8~2.4m3h-1的气速范围内,由静压力、导流管顶部截面流体速度、全床气含率(及传质系数)周期性变化所确定的振荡周期TP、TV、TK比稳态操作下的全床平均传质系数分别提高了3.92%~27.3%,2.35%~24.5%,28.2%~43.3%。由反应器内全床平均气含率或传质系数确定的振荡周期TK是最佳振荡周期。 相似文献
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多相机械搅拌气升式环流反应器中的气液传质 总被引:3,自引:0,他引:3
由空气水玻璃珠(ρ=2630kg/m3,dp=25μm)构成三相体系,在内置机械搅拌桨的内循环反应器中进行实验。实验条件:表观气速Ug0.5~19.0cm/s,固含量εs1%、2%、4%(质量分数),搅拌桨速度为0~1200r/min。结果表明总体积传质系数KLa随气体表观气速和搅拌速度增加而增加。总能量耗散速率同时受通气能量耗散速率与搅拌机械能量耗散速率的影响。搅拌转速一定时,搅拌机械能量耗散速率随表观气速的增加而下降。从能量角度考虑,表观气速和搅拌速度的选择应有一个良好的匹配。存在固体颗粒时,传质系数KLa与传质界面面积a均得到改进。对于25μm玻璃珠体系,KLa值随固含率变化,其最大值的产生在2%固含率左右,固含率继续增加,则KLa降低。最后对KLa固含率及能量耗散速率作了关联。 相似文献
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气升式振荡环流反应器(ARLR)作为一种新型的气升式环流反应器,能够有效地提高反应器的气含率和传质系数,并已得到生物发酵实验的验证。本文通过CFD的手段研究了反应器内的流动和传质状况,并利用CFD模拟和响应面分析相结合的方法,优化了反应器的结构参数,如高径比(H/D)、升液区降液区面积之比、导流筒高度等。经过实验测量,优化后的气升式振荡环流反应器与传统的气升式环流反应器相比,气含率提高了32%以上,传质系数提高了11%以上。结果表明,气升式振荡环流反应器作为生化反应器有着非常广阔的应用空间。 相似文献
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吴松 《化学反应工程与工艺》2023,(2):117-125
在气升式反应器冷模实验装置中,研究了气体分布器类型及结构参数对流场和传质的影响规律。结果表明:与环形分布器和四喷嘴分布器相比,采用半球形分布器时平均气含率更高、气含率径向分布更均匀、气泡直径更小、比表面积更大、下降段液速更大、液相体积传质系数更高。气升式废水处理反应器中选用半球形气体分布器可获得更好的混合和传质效果。进一步考察了半球形分布器开孔率和开孔角度对气含率、下降段液速和体积传质系数的影响,确定了最优开孔率为0.457%、最优开孔角度为45o。研究结果可为气升式反应器的工业设计和操作优化提供依据。 相似文献
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Spheripol工艺生产高抗冲聚丙烯 总被引:1,自引:0,他引:1
介绍了Spheripol工艺生产高抗冲聚丙烯产品的方法,采用两步复合工艺生产嵌段聚丙烯,第1步采用环管反应器进行丙烯液相均聚反应,第2步采用流化床反应器进行丙烯均聚物与乙烯单体气相共聚反应,即在气相反应器中,利用来自环管反应器中的均聚物的残余活性,加入乙烯和补充的丙烯及氢气实现乙-丙共聚,共聚物的生成使最终产品的抗冲性能大大提高,尤其是低温下的抗冲性能。 相似文献
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The rates of electropolishing of vertical copper plates in H3PO4 placed downstream of a H2 evolving cathode were studied by measuring the limiting current of the diffusion controlled process under different conditions of H2 discharge rates and H3PO4 concentrations. The mass transfer coefficient was found to increase with H2 discharge rate raised to the exponent of 0.4. Within the studied experimental range of conditions, the rate of polishing increased by a factor ranging from 1.95–5.8, depending on the H2 discharge rate and H3PO4 concentration compared to the natural convection value. The results are explained in terms of surface renewal theory. The proposed electrochemical reactor offers the advantage of increasing the rate of electropolishing without consuming external stirring energy as opposed to traditional electrochemical reactors. 相似文献
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Keun Ho Chof 《Korean Journal of Chemical Engineering》1999,16(4):441-448
A mathematical model for simulation of unsteady-state oxygen transfer in an external-loop airlift reactor was developed. The
airlift reactor was represented by a number of interconnected tanks, each of which was assumed to be well mixed. The effect
of gas circulation rate on the oxygen transfer was considered. The model can be used for the determination of mass transfer
performance of the airlift reactor in which the whole liquid phase cannot be assumed to be fully backmixed. The simulation
results showed a good agreement with experimental results. 相似文献
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Nalinee Tunthikul Porntip Wongsuchoto Prasert Pavasant 《Korean Journal of Chemical Engineering》2006,23(6):881-887
The draft tube configuration significantly affected the performance of an airlift contactor. The multiple draft tube configuration
was demonstrated to give a better gas-liquid mass transfer when compared with a conventional one-draft-tube system. The airlift
with a larger number of draft tubes allowed a higher level of bubble entrainment, which rendered a high downcomer gas holdup.
This resulted in a higher overall gas holdup in the contactor. Liquid velocity was also enhanced by increasing the number
of draft tubes. The ratio between downcomer and riser cross sectional areas, A
d
/A
r
, had a great effect on the system performance, where a larger A
d
/A
r
led to a lower downcomer liquid velocity and smaller quantity of gas bubbles being dragged into the downcomer. This resulted
in low gas holdup, and consequently, low gas-liquid interfacial mass transfer area, which led to a reduction in the overall
volumetric mass transfer coefficient. The presence of salinity in the system drastically reduced the bubble size and subsequently
led to an enhancement of gas entrainment within the system. As a result, higher gas holdups and gas-liquid interfacial area
were observed, and hence, a higher rate of gas-liquid mass transfer was obtained. 相似文献
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The dynamic Characteristics of a Fluidized Catalytic Cracking Process are examined over a wide range of operating conditions. A novel Order of Magnitude Approach is introduced to successfully provide physical insight into the cause and effect relationship between operating conditions and dynamic characteristics. It is shown that the original five-dimensional dynamic model is characterized by three fast time constants and two slow ones that dominate the dynamic responses. The two most important time constants are expressed as explicit functions of the operating conditions. These formulas correctly indicate in which parameter regions the open loop response is oscillatory (underdamped) or nonoscillatory (overdamped). Extensive process variables, that are either flow or capacity, related are defined in order to provide an approximate physical meaning for the dynamic modes of the system. It is shown that the two slow modes of the process are related to the enthalpy content of the regenerator and the sensible heat content of the catalyst phase in both the reactor and regenerator. 相似文献
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Molten salt oxidation process is one of the most promising alternatives to incineration that can be used to effectively destroy
the organic components of mixed and hazardous wastes. To detect the flow characteristics of the molten salt oxidation process
(air-molten carbonate salt two-phase flow), differential pressure fluctuation signals from a molten salt oxidation process
have been analyzed by adopting the stochastic methods. Effects of the input air flow rate (0.05–0.22 m/sec) and the molten
salt temperature (870–970 °C) on the phase holdup and flow characteristics are studied. The gas holdup increases with an increasing
molten salt temperature due to the decrease of the viscosity and surface tension of the molten carbonate salt. It is found
that a stochastic analysis of the differential pressure signals enables us to obtain the flow characteristics in the molten
salt oxidation process. The experimentally obtained gas holdup data in the molten salt reactor were well described and characterized
by means of the drift-flux model.
This work was presented at the 7th China-Korea Workshop on Clean Energy Technology held at Taiyuan, Shanxi, China, June 26–28, 2008. 相似文献
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Simple, explicit and physically intuitive Feedforward and Feedback control policies are designed for Fluidized Catalytic Cracking Processes. The Feedforward (FF) control algorithm compensates for changes in the feed rate and feed coking tendency by the use of the air flow and catalyst circulation rates as control variables to maintain the conversion and the reactor temperature at fixed levels. Through steady state and dynamic simulations the FF controller is shown to be very effective. To improve the dynamic response of the process and to account for the process/model mismatch a feedback (FB) controller is also designed to complement the FF action. The FB action is designed by use of the transformation related to the physical modes which correspond to the extensive variables of the process. It is shown that the required control structure consists of two loops. One uses the air flow rate to control the total sensible heat content of the reactor and regenerator solid phases. The other loop controls the regenerator enthalpy by changes in the catalyst circulation rate. The air flow rate controller includes an integral action to avoid reactor temperature offsets, while the catalyst circulation rate controller requires a nonlinear static observer to predict the coke concentration on the regenerated catalyst from dense bed and flue gas regenerator temperatures. The performance of the controller for changes on the oil feed rate, caking tendency of the feed, as well as for reactor temperature set point changes is faster and smoother than Kurihara's scheme. 相似文献
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连续搅拌釜式丙烯聚合反应器的模拟(Ⅰ)反应器的定态模拟 总被引:4,自引:0,他引:4
以实际工业装置为背景,建立了丙烯液相本体聚合连续搅拌釜式反应器的定态数学模型。通过模拟计算,考察了诸工艺参数──进料温度、进料流量、夹套冷却水人口温度和流量、丙烯蒸汽冷凝量、催化剂浓度以及反应器中的氢浓度对聚合反应釜反应结果的影响,并对其定态操作行为作了理论上的解释和分析。 相似文献
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The heat transfer effect of an inert gas on a multi-tubular reactor for a partial oxidation reaction has been determined.
The model reaction system in the study was partial oxidation of propylene to acrolein. Both theoretical modeling and experimental
studies have been performed to determine the heat transfer effect of inert gas on the system. Among many inert gases, CO2 was selected and tested as a diluent gas for the partial oxidation of propylene to acrolein system instead of conventionally
used N2. The productivity increase through changing the inert gas from N2 to CO2 was possible due to the heat transfer capability of CO2. In this study, by replacing the inert gas from N2 to CO2, productivity increased up to 14%. 相似文献