基于CFD的强化裂解炉管设计

通过计算流体力学(CFD)的方法,将丙烷裂解反应动力学与流动方程、能量方程耦合,考察了在普通裂解炉管中加装中空立交盘(hollow cross-disk,HCD)内构件对管内流动及裂解反应的影响。结果发现,HCD内构件通过壁面几何形状变化重布了流场结构,以合理的压力损失为代价产生径向速度,并诱导产生纵向涡剪切破坏边界层,强化了流体的湍动程度,降低热阻,提高了温度分布均匀性。相比于普通炉管,加入中空立交盘后,裂解管丙烷转化率提高7.24%,烯烃选择性提高3.67%,乙烯收率降低0.87%,但丙烯收率大幅上升16.50%,烯烃总收率上升6.94%。此外发现,纵向涡产生的径向流动促进了近壁区高温流体和管中心区相对低温流体的换位,流体温度最高下降了0.7℃;与普通炉管相比,新型裂解管出口处重组分浓度下降了28.33%,说明加入中空立交盘可防止近壁面高温区域过度裂解,有助于抑制结焦。在此基础上,结合模拟所得的场分布数据,定量分析了HCD强化传热和传质的机理,并就阻力损失和强化效果做出综合评价。     

裂解炉横跨管的设计

裂解炉横跨管的设计对辐射段炉管的变形有较大的影响，通过对己建成投产的裂解炉横跨管的设计及使用情况进行总结，以及对横跨管设计的几个方案进行比较，对横跨管设计提出了比较合理的方案，此方案已在中原，天津等裂解炉的设计中采用，并取得良好效果。     

一种新型裂解炉炉管强化传热数值模拟

利用计算流体动力学(computational fluid dynamic,CFD)方法对含新型内插件强化传热辐射炉管(fortified induced turbulence,FIT)进行了流体流动与传热特性的研究,采用RNG双方程模型求解了动量方程和能量方程,给出了FIT炉管内的流体流动和传热特性,包括速度场、湍动强度和温度场的分布;计算了FIT炉管的强化传热因子和压降。研究结果表明,FIT炉管内插件迫使流体流动由活塞流转变为旋转流,增强了流动湍流程度,符合流动-能量场协同理论,同时流体边界层由于FIT炉管的特殊结构而减薄。FIT炉管具有增强辐射传热、减薄边界层、增加比表面积和旋流增强等强化传热特性。相比于普通当量圆炉管,FIT强化传热炉管的整体传热能力提高了20%左右,证明该新型炉管强化传热效果显著,可以在工程实际中应用。     

裂解炉出口管热电偶密封结构的改进

介绍裂解炉出口热电偶结构形式的设计改进，新结构形式热电偶密封材料的选择及生产运行，新结构形式特点，密封性好，方便维修。     

裂解炉用高强度高耐腐蚀挤压管的开发

乙烯装置裂解炉,因炉管内壁处于渗碳气氛之中,故要求炉管除具有高温强度外,还要求具备优越的耐渗碳性。以前,通常使用内径为3～4英寸的大直径离心铸造管。近年来,     

烯烃装置裂解炉配置中计算流体力学的应用

德国Linde工程公司的博士介绍，工业上制聚烯烃主要通过长链烃类的吸热裂解。为此，原料通过置于燃烧室中外侧加热的裂解管而裂解。最近，进行物流模拟的工业数值计算技术达到了可成功地应用于工业炉的水平。原则上可根据流体力学、燃烧和传热来描述裂解管之间关于对流和辐射传热的作用。     

裂解炉管结焦抑制剂开发及应用

裂解炉炉管结焦抑制剂工业应用在国内尚属首次，上海石化与华东理工大学联反所联合开发并投入了工业应用，文中介绍了该抑制剂的开发与工业应用过程，并指出了目前应用抑制剂取得良好效果的一些原则。     

裂解炉管的蠕变应力计算模型

通过对乙烯裂解炉管运行工况的分析 ,在金属扩散理论与渗碳失效机理的基础上提出了渗碳产生的应力计算方法。对HP Nb材料制成的乙烯裂解炉管在 832～ 90 2℃下的应力场进行了模拟 ,分析了炉管在温度、内压、渗碳和蠕变等交互作用下炉管管壁应力的分布情况。结果表明 ,渗碳是引起炉管失效的主要因素。     

裂解炉用扭曲片管铸造工艺

目前扭曲片管已较广泛地应用于裂解炉辐射炉管上,通过介绍扭曲片管的几种铸造工艺,并对不同铸造工艺下扭曲片管的无损检测以及力学性能进行分析,从而阐明不同铸造工艺的优缺点.     

计算流体力学在裂解炉设计上的应用

阐述了计算流体力学(CFD)在石油化工领域，特别是在裂解炉技术上的应用。内容共分两部分：1．国外公司在裂解炉设计及故障诊断中CFD软件的应用简介。2．应用CFX软件对裂解炉中的关键技术的模拟、分析及计算情况的综述。     

Rheokinematics for product development—Formulation screening in rotational rheometers

Product formulations for industrial processes are typically developed at laboratory scale. However, the mixing conditions are not easily mimicked in the laboratory. A rotational device is proposed in this study as a fast laboratory-scale formulation development, which enables mimicking the mixing conditions in the industrial process. The geometrical configurations of the rotational device are from rheometry devices (plate-plate and cone-plate). The main advantages of this method are the small amounts of raw materials and shorter testing times. This methodology is applied to an industrial case study, the reaction injection molding (RIM) process. The mixing length scales evolution in the rotational rheometer were matched to those in RIM machines. The main novelty of this study is the introduction of a protocol that bridges the processing conditions at laboratory using small amounts of raw materials to high throughput continuous flow reactors.     

FCC提升管反应器中终止剂注入对裂化反应的影响

通过对催化裂化提升管注入终止剂前后的工况进行数值模拟,研究了终止剂注入对提升管内速度分布、催化剂颗粒浓度分布、温度分布以及组分浓度分布的影响,考察了不同注入量以及注入高度的终止剂在提升管内的作用区域及其对裂化反应的影响。研究表明,终止剂的注入大幅提升了提升管内的油气速度,降低了催化剂浓度、油气和催化剂的温度,使得提升管内原料的裂化程度降低,二次反应减少。且不同注入量和注入高度的作用区域不同,对裂化反应的影响不同,应根据实际工况进行分析。     

搅拌萃取塔内单相流动不同雷诺平均湍流模型结果的比较

The flow field of liquid phase (water) of agitated extraction columns is simulated with the help of computational fluid dynamics (CFD). Four kinds of Reynolds-averaged turbulence models, i.e. the standard k-ε model, the RNG (renormaiization group) k-ε model, the realizable k-ε model and the Reynolds stress model, are compared in detail in order to judge which is the best model in terms of the accuracy, less CPU time and memory required. The performance of the realizable k-ε model is obviously improved by reducing the model constant from c2 = 1.90 to c2 = 1.61. It is concluded that the improved realizable k-ε model is the optimal model.     

含列管束鼓泡塔的CFD模拟:湍流模型的影响

含列管束鼓泡塔的CFD模拟结果准确性与相间作用力模型、湍流模型等封闭模型有关。本工作考察了常用的6种湍流模型(标准k-ε、RNG k-ε、Realizable k-ε、标准k-ω、SST k-ω和RSM)对不含内构件及含列管束的中试规模鼓泡塔内流体动力学的影响。结果表明;RSM预测的空塔内流体的湍流动能、湍流耗散率和湍流黏度均远高于涡黏模型(k-ε模型、k-ω模型);但在模拟列管塔时这种差距明显缩小;而且列管显著抑制了液相的湍动程度。同时;将鼓泡塔内气含率及轴向液速的模拟值与实验测量数据进行了对比;发现涡黏模型仅可准确预测空塔内中心区域气含率而RSM可预测其余区域气含率;6种湍流模型预测的列管塔内气含率径向分布几乎一致;Realizable k-ε模型预测的空塔及列管塔内轴向液速值与实验数据高度吻合;明显优于其他湍流模型;在模拟鼓泡塔内流体力学时推荐使用。     

A new differential pressure flow meter for measurement of human breath flow: Simulation and experimental investigation

The development and performance characterization of a new differential pressure‐based flow meter for human breath measurements is presented in this article. The device, called a “Confined Pitot Tube,” is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics^® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method. © 2016 American Institute of Chemical Engineers AIChE J, 62: 956–964, 2016     

Direct numerical simulation of the turbulent flow in a baffled tank driven by a Rushton turbine

We present a direct numerical simulation (DNS) of the turbulent flow in a baffled tank driven by by a Rushton turbine. The DNS is compared to a Large Eddy Simulation (LES), a Reynolds Averaged Navier‐Stokes (RANS) simulation, Laser Doppler Velocimetry data, and Particle Image Velocimetry data from the literature. By Reynolds averaging the DNS‐data, we validate the turbulent viscosity hypothesis by demonstrating strong alignment between the Reynolds stress and the mean strain rate. Although the turbulent viscosity ν_T in the DNS is larger than in the RANS simulation, the turbulent viscosity parameter C_μ = ν_T?/k², is an order of magnitude smaller than the standard 0.09 value of the k‐? model. By filtering the DNS‐data, we show that the Smagorinsky constant C_S is uniformly distributed over the tank with C_S ≈ 0.1. Consequently, the dynamic Smagorisnky model does not improve the accuracy of the LES. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Computational fluid dynamics‐based steam cracking furnace optimization using feedstock flow distribution

Nonuniform temperature fields in steam cracking furnaces caused by geometry factors such as burner positions, shadow effects, and asymmetry of the reactor coil layout are detrimental for product yields and run lengths. The techniques of adjusting burner firing (zone firing) and feedstock mass flow rate (pass balancing) have been practiced industrially to mitigate these effects but could only reduce the nonuniformities between the so‐called modules (a group of many coils). An extension of the pass balancing methodology is presented to further minimize the intra‐module nonuniformities, that is, variation between the coils within a module, in floor fired furnaces. Coupled furnace‐reactor computational fluid dynamics‐based simulations of an industrial ultraselective conversion (USC) furnace were performed to evaluate four different feedstock flow distribution schemes, realizing equal values for coil outlet temperature, propene/ethene mass ratio, maximum coking rate and maximum tube metal temperature (TMT), respectively, over all the reactor coils. It is shown that feedstock flow distribution creates a larger operating window and extends the run length. Out of the four cases, the coking rate as criterion leads to the highest yearly production capacity for ethene and propene. Uniform maximum coking rates boost the annual production capacity of the USC furnace with a nameplate ethene capacity of 130 10³ metric tons per year with 1000 metric tons for ethene and 730 metric tons for propene. For industrial application, achieving uniform maximum TMT is more practical due to its measurability by advanced laser‐based techniques. Most steam cracking furnaces can be retrofitted by optimizing the dimensions of venturi nozzles that regulate the feedstock flow to the coils. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3199–3213, 2017