浅谈液相催化加氢反应器的搅拌和换热

介绍了液相催化加氢反应器最重要的2点设计:搅拌器和换热。分析了各种搅拌器的特点、性能,并进行了互相对比,特别是对自吸式搅拌器结构特点、工作原理、性能做了详细介绍,认为自吸式搅拌器是所有搅拌器中气液传质效果最好的搅拌器,它的应用提高了加氢反应速率和氢气的利用率;对加氢反应器的换热盘管或夹套与传热板进行了比较,传热板的应用提高了传热效果,认为自吸式搅拌和高效率的传热板应用于液相催化加氢反应中是一种最新型的液相催化加氢反应器。     

加氢操作反应机理及装置功能特性

通过反应物传质模型论述了加氢反应装置的反应机理;分析了反应阻力与其影响因素之间的关系;介绍了搅拌槽型加氢反应装置的结构形式和操作过程;以混合型加氢反应器和自吸式搅拌槽为例,论述了加氢反应器的性能特征、主要功能和技术管理要点。     

基于自吸式搅拌的液相催化加氢模拟试验系统设计

建立了一套液相催化加氢模试系统,为工业化装置的设计提供实验数据,模试装置宅反应器设计容积20 L,压力6.4MPa,温度300℃.系统主要由反应器、进样系统、采样系统、催化剂回收系统、加热系统、冷却系统、控制系统组成.该系统具有以下特点:主反应器采用杭州原正化学工程技术装备有限公司专利自吸式搅拌器,可提供较大的气液接触面积和反应速率;在线采样系统可以取得不含催化剂的样品;催化剂回收系统可进行催化剂的回收利用;PLC控制系统可对反应温度、压力、氢气流量、冷却水流量、冷却上下水温度进行控制和记录.本模试系统能为液相催化加氢技术的工业化提供重要的动力学和热力学数据.     

自吸式搅拌反应器的研究进展

自吸式搅拌反应器以搅拌桨的机械搅拌产生的压差吸入气体,可以显著提高传质系数,减少功率消耗,在工业中具有广阔的应用前景。从实验研究、数值模拟、实验研究与数值模拟相结合三方面对自吸式搅拌反应器的研究现状进行了阐述,指出对自吸式搅拌反应器的放大、振动、动平衡进行分析,是指导自吸式搅拌反应器工业应用的有效途径。     

环路反应器制备饱和脂肪酸甲酯的研究

用环路反应器进行椰油酸甲酯加氢制饱和甲酯的结构同搅拌釜对照，反应周期缩短６０％，对实验结果进行了动力学分析，表明环路反应器加氢为二级反应，搅拌釜加氢为一级反应。     

共轭双烯聚合物选择性加氢反应器技术进展

对以橡胶、弹性体为代表的含共轭双烯聚合物进行烯属双键的选择性加氢,可显著提高聚合物的稳定性;加氢反应器和反应工艺是制约加氢度和产率的关键技术之一。该文综述了目前共轭双烯聚合物选择性加氢反应器的技术进展,包括以机械搅拌反应器、鼓泡反应器、外循环反应器为代表的全混流型反应器;以填料塔和静态混合管式反应器为代表的平推流型反应器;以及各种反应器的组合技术、特殊操作方式。结合加氢体系的流体力学特征和反应动力学特征,分析了制约加氢度和产率的关键问题,总结了进一步提高加氢度和产率、降低能耗物耗的潜在途径。     

连续液相柴油加氢装置降低反应器压降新技术应用

分析了某套连续液相柴油加氢装置反应器压降升高的原因以及带来的不利影响，探索了在停开反应循环泵且不改变加工焦化汽油、焦化柴油原料的情况下继续维持装置高负荷生产超低硫柴油的可行性。通过多次技术攻关和调整摸索，开发出了一种连续液相柴油加氢装置反应器反向吹扫新技术，通过利用装置现有流程，实现了对上流式反应器进行反向冲洗和吹扫，有效解决了反应器压降高的问题，使装置运行周期提高了2年左右。在1个生产周期内，该技术可以反复多次使用，每次反向吹扫可以降低反应器压降0.2 MPa以上，显著改善了装置运行工况，装置运行周期可延长4个月以上，避免了装置提前停工并更换催化剂。反应器反向吹扫技术简单、高效，可推广至使用上流式反应器的多种加工工艺，可有效解决常规滴流床反应器压降容易升高且不得不停工处理的固有技术难题，具有较好的推广价值和应用前景。     

汽油加氢炉反区管线应力分析要点探讨

近几年来,国内加氢技术得到长足发展,加氢装置在炼油和石油化工企业中受到重视。加氢反应器与加热炉是加氢装置中非常重要的核心设备,操作条件比较苛刻,具有高温、高压、临氢等特点。炉反区的管线应力分析尤为重要。以某石化公司40万t/a催化汽油加氢装置中的炉反区应力计算过程为例,总结汽油加氢炉反区管线应力分析要点,对该管系应力分析过程中遇到的问题进行讨论。     

无定子自吸式生化反应器的结构特点及吸气构件的设计计算

自吸式生化反应器是六十年代开始研究的一种新型的反应器,七十年代我国的自吸式反应器有较大发展,特别是在医药工业,酵母工作收效显著。反应器在搅拌过程完成充气的作用,从而省去动力消耗大的空压机和庞大的空气净化系统,能耗大大降低。作者在华南工学院高孔荣教授的亲自指导下,根据10升试验反应器发酵食醋的研究试验,比拟放大为10米~3无定子自吸式反应器,是国内目前最新型的无定子自吸式反应器。对于设计的结构特点和搅拌吸气构件的参数设计计算,本文作一点介绍,供有关同志参     

蜡油液相加氢装置处理催化柴油可行性研究

国内某石化企业在加氢裂化装置检修期间催化柴油无法处理,为解决柴油物料平衡问题,考虑将催化柴油临时进入蜡油液相加氢装置处理.为验证该方案的可行性,中国石化大连石油化工研究院在液相加氢中试装置进行可行性试验研究.结果表明:利用蜡油液相加氢装置处理催化柴油是可行的,在反应压力13.8 MPa、平均反应温度350℃、新鲜进料体...     

具有双层桨结构的自吸式搅拌反应器的流体力学性能

在直径0.48 m的搅拌槽中以水?空气为介质,对具有双层桨结构的自吸式反应器的流体力学性能进行了实验研究,考察了自吸式桨浸没深度、底层桨结构和搅拌桨层间距对自吸式桨的临界吸气转速、吸气速率和气含率的影响。结果表明,临界吸气转速随自吸式桨浸没深度增加而增加,临界吸气转速几乎与下层桨的结构无关;吸气速率与气含率随浸没深度增加而减小,吸气速率与气含率受下层桨影响较大,层间距为自吸式桨直径(D)且采用上推式的四叶宽叶翼形轴流式桨作下层桨时,自吸式桨的吸气性能最佳。     

Liquid flow in impeller region of an unbaffled agitated vessel with an angularly oscillating impeller

The characteristics of a liquid flow were studied in the impeller region of an unbaffled agitated vessel with an angularly oscillating impeller whose unsteady rotation proceeds while periodically reversing its direction at a set angle. The measurement of the velocity of the liquid flow was performed by particle tracking velocimetry (PTV), abreast of that of the torque of the shaft to which the impeller was attached. When a disk turbine impeller with six flat blades was used with variations in operating conditions, such as the frequency and amplitude of impeller angular oscillation, a series of images obtained during one oscillation cycle were analyzed to characterize the internal and discharge streams inside and outside the impeller rotational region. Energy data were inferred on the basis of the circumferential and radial velocities of an internal flow. Results showed that although the total head provided to the liquid by the impeller blades is almost similar, independent of the amplitude of impeller angular oscillation, namely, the acceleration of its movement, the transformation of energy from the pressure head to the velocity head is more efficient at a larger amplitude. In addition, the discharge flow was characterized in terms of volumetric flow rates calculated from the radial and axial velocities. The operation at a smaller amplitude was shown to transform the flow more successfully from the radial direction to the upward and downward axial directions near the vessel wall.     

Review on Mixing Characteristics in Solid‐Liquid and Solid‐Liquid‐Gas Reactor Vessels

Mechanically agitated reactors with single and multiple impeller systems are used in the industry for the various three‐phase mixing processes such as crystallization, fermentation, and hydrogenation, etc. The paper reviews the experimental work reported in the literature along with different techniques used for the measurement of the specific quantities such as minimum or critical impeller speed for solid suspension. The work critically surveys the literature and makes specific recommendations for the use of appropriate correlations and conditions to be used for the success of such equipment. This assessment will put all the relevant literature on a common footing and will help to validate work reported earlier.     

Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward–reverse rotating impeller

For an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop–reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward–reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine‐type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance.     

Gas recirculation rate and its influences on mass transfer in multiple impeller systems with various impeller combinations

Both the numerical and experimental approaches were used to study the effects of the gas recirculation and non‐uniform gas loading on the mass transfer rate for each impeller in a multiple impeller system. By combining the calculated gas velocity and local gas holdup, the gas recirculation rate around each impeller was estimated. The local mass transfer coefficients for systems equipped with various combinations of the Rushton turbine impeller (R) and pitched blade impeller (P) were determined by using the dynamic gassing out method. It is found that the Rushton turbine impeller has to be served as the lowest impeller in order to have a better gas dispersion and to give a higher overall K_La for a multiple impeller gas‐liquid contactor. The upper pitched blade impeller always enforces the circulating flow around the Rushton turbine impeller just beneath it and gives a higher overall average mass transfer rate. However, the system equipped with only the pitched blade impellers results in a much lower mass transfer rate than the other systems owing to the poor gas dispersion performance of the pitched blade impeller.     

Performance characteristics of an axial-flow gas induction impeller

Power number, pressure coefficient, and induced gas flow rate of a novel axial-flow gas induction impeller with large openings for gas flow are reported. The effects of rotational speed, impeller diameter, submergence, and pumping mode are considered in turbulent operation. The pressure coefficient is measured using the reduction in pressure at speeds below the minimum induction speed as well as from the minimum induction speed. The minimum induction speed approach consistently yields lower pressure coefficient values, indicating the existence of impeller exit losses that are required to force gas from the centre of the impeller into the liquid. The induced gas flow rate is modelled using two approaches. The first approach relates the gas flow rate to the available pressure difference, and in this case, the relation is found to be strongly affected by impeller diameter. The second approach is a literature model that likens the induction process to water jet injection. While this approach appears promising, flow measurement device pressure losses make it difficult to definitively evaluate this method.     

通气条件下桨型对自浮颗粒悬浮的影响

考察了五十二种搅拌桨的组合对搅拌釜内自浮颗粒的气液固三相体系混合问题的功耗、气含率和釜底部的颗粒含量的影响。研究表明 ,对自浮颗粒三相体系的搅拌混合应采用多层桨 ,且上层最好用上推式桨 ;实验发现 ,当高径比为 1 .6时 ,三层桨的混合参数优于两层桨的 ;给出了优异的搅拌桨型。     

新型组合桨混合性能研究

根据聚合反应的特定工艺过程要求,提出了一种新型双轴搅拌桨,并设计实验对其宏观混合性能进行研究,与常规桨型进行对比,结果表明该桨在高粘度流体内混合时间、排液量、混合效率等方面较常规桨型好。不但能在较短的时间内实现全罐的均匀混合,没有死角,而且还具有节能降耗的优点。     

搅拌槽中非稳态温度场分布的研究

在对称装有4组垂直加热列管、直径为500mm的搅拌槽中使用长薄叶(CBY)桨进行搅拌,采用液晶(LC)测温技术测量搅拌槽内温度场的分布。分别研究了搅拌槽中轴向温度分布随加热时间、叶轮雷诺数以及桨的安装高度不同而变化的情况。结果表明,列管加热时间的长短对槽内温度分布的趋势没有影响,温度分布的趋势主要取决于所用搅拌桨产生的流型;随着叶轮雷诺数的增加,槽内温度分布相对趋于均匀;搅拌桨的安装高度对温度场的分布影响也很显著。