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MP-PIC simulation of circulating fluidized beds using an EMMS based drag model for Geldart B particles

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Particuology 2021年第6期19卷 76-90页

作者： Timo Dymala Tom Wytrwat stefan heinrich Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestr.1521073 HamburgGermany

In this study the multiphase particle-in-cell(MP-PIC)method is used for the simulation of two pilot-scale circulating fluidized beds(CFBs)with quartz sand belonging to Geldart’s group B as bed *** simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method(EMMS).The results are compared with experimental data from literature as well as *** simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration,circulation rate and riser pressure ***,a lower grid sensitivity is observed compared to the homogeneous drag *** contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag *** overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter *** shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B ***,the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is ***,the importance of using a realistic particle size distribution is identified.

关键词： 3D-CFD simulation Circulating fluidized bed(CFB) Multiphase particle-in-cell method(MP-PIC) Energy minimizing multi-scale theory(EMMS) Validation study

Pathological tumor response to neoadjuvant therapy in borderline resectable pancreatic cancer

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Hepatobiliary & Pancreatic Diseases International 2019年第4期18卷 305-306页

作者： stefan heinrich General Visceral and Transplantation Surgery University Hospital of Mainz

Surgery is the standard therapy for pancreatic ductal adenocarcinoma(PDAC).After the dramatic decline of operative mortality over the past decades,the indications for pancreas resections have been continuously extended:currently resections of the portal/superior mesenteric vein are considered standard by many centers,and even arterial resections are under *** these changes,different expert groups have defined resectability criteria containing a grey zone(“borderline resectable disease”)of tumors,which may be technically resectable with appropriate surgical expertise,but resection inherits an increased risk of an R1-resection[1].

关键词： Surgery mortality operative

Simulation of spray coating in a spouted bed using recurrence CFD

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Particuology 2019年第1期17卷 92-103页

作者： Paul Kieckhefena Thomas Lichtenegger Swantje Pietsch stefan Pirker stefan heinrich Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology. HamburgGermany Department for Particulate Flow Modelling. Johannes Kepler University LinzAustria Linz Institute of Technology (LIT) Johannes Kepler UniversityLinzAustria

Although numerical models such as the computational fluid dynamics–discrete element method (CFD–DEM) have enabled the accurate simulation of laboratory-scale apparatuses, the application of these methods to large-scale apparatuses with many particles and time scales ranging from minutes to hours remains a challenge. The recently developed recurrence CFD (rCFD) method seeks to overcome these issues in pseudo-periodic processes by extrapolating globally recurring patterns in a physically meaningful way and describing the transport and interaction of passive scalars using Lagrangian tracers. Spouted beds represent an interesting target because of the associated variety of flow regimes. They can be effectively described by CFD–DEM on the time scale of tens of seconds, whereas industrially relevant processes typically take hours. In this contribution, we established the validity of applying the Lagrangian rCFD method to spouted beds by demonstrating the accurate reproduction of the particle residence time distribution in a fictitious spray zone. The deposition of spray droplets onto tracer particles was simulated for 1 h, and the particle surface coverage distribution was estimated using a statistical approach for both an unstabilized prismatic spouted bed and one stabilized by draft plates.

关键词： CFD–DEM Recurrence CFD Spray coating Time-scale decoupling Spouted bed Draft plate

Product design based on discrete particle modeling of a fluidized bed granulator

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Particuology 2014年第1期12卷 13-24页

作者： Lennart Fries Sergiy Antonyuk stefan heinrich Gerhard Niederreiter stefan Palzer Nestlé Research Center Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Fluidized bed agglomeration is a process commonly used to construct powdered food or pharmaceuti cal products to improve their instant properties. This works analyzes the influence of a wide range of operating parameters （i.e., fluidization air flow rate, temperature, and liquid injection rate） on growth rate, process stability, and product particle structure. Different granulator configurations （i.e., top spray, Wurster coater, spouted bed） are compared using identical process parameters. The impacts of both pro cess variables and granulator geometry on the fluidization regime, the particle and collision dynamics, and the resulting product structure and corresponding properties are studied in detailed simulations using a discrete particle model （DPM） and labscale agglomeration experiments with amorphous dextrose syrup （DE21）. The combination of numerical and experimental results allows to correlate the kinetics of micro scale particle interactions and the final product properties （i.e., agglomerate structure and strength）. In conclusion, detailed DPM simulations are proven as a valuable tool for knowledgebased product design.

关键词： FluidizationAgglomerationDiscrete element methodFood powderCollision dynamics

Why surgeons care about systemic chemotherapy for pancreatic cancer?

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Hepatobiliary Surgery and Nutrition 2021年第6期10卷 860-863页

作者： stefan heinrich Department of General Visceral and Transplantation SurgeryUniversity Hospital of MainzMainzGermany

Pancreatic adenocarcinoma(PDAC)has become the seventh most frequent cause of cancer death in the world with increasing incidence independent of patient sex and age with smoking and alcohol consumption being the most important risk factors(1).The high mortality rate is mainly attributed to the biological characteristics of this disease:even small tumors reveal perineural invasion or local spread into lymph and blood vessels resulting in systemic *** estimated risk of occult distant metastasis at the time of surgery is 28%and 94%for tumors with a diameter of 1 and 3 cm,respectively(2).Consequently,many patients present with disseminated or locally advanced disease and are at high risk for early tumor recurrence(3).

关键词： cancer invasion mortality

The current role of liver surgery in the treatment of colorectal liver metastases

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Hepatobiliary Surgery and Nutrition 2019年第5期8卷 552-554页

作者： stefan heinrich General Visceral and Transplantation SurgeryUniversity Hospital of MainzMainzGermany

Since the establishment of a survival benefit for patientswith colorectal cancer liver metastases(CRLM)undergoingliver resection,perioperative outcome has continuouslyimproved,and surgery for CRLM is currently offered... 详细信息

关键词： colorectal surgery metastases

Neoadjuvant therapy for pancreatic ductal adenocarcinoma—real effects or patient selection?

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Hepatobiliary Surgery and Nutrition 2018年第4期7卷 289-291页

作者： stefan heinrich Department of General Visceral and Transplantation Surgery University Hospital of Mainz Mainz Germany

Surgery is the only treatment with curative potential for patients with pancreatic ductal adenocarcinoma (PDAC).Unfortunately, the majority of patients do not qualify for curative resection due to locally advanced or ... 详细信息

关键词： adenocarcinoma Surgery curative

Influence of liquid layers on energy absorption during particle impact

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Particuology 2009年第4期7卷 245-259页

作者： Sergiy Antonyuk stefan heinrich Niels Deen Hans Kuipers Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Denickestr. 15 21071 Hamburg Germany University of Twente Fundamentals of Chemical Reaction Engineering Faculty of Science and Technology PO Box 217 Enschede 7500 AE The Netherlands

The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic-plastic γ- Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity （1-300 mPa s）, In the presence of a liquid layer, increase of liquid viscosity decreases the restitution coefficient and the minimum thickness of the liquid layer at which the granule sticks to the wall. The measured restitution coefficients were compared with experiments performed without liquid layer. In contrast to the dry restitution coefficient, due to viscous losses at lower impact velocity, higher energy dissipation was obtained, A rational explanation for the effects obtained was given by results of numerically solved force and energy balances for a granule impact on a liquid layer on the wall. The model takes into account forces acting on the granule including viscous, surface tension, capillary, contact, drag, buoyancy and gravitational forces. Good agreement between simulations and experiments has been achieved.

关键词： Granule impact Restitution coefficient Energy dissipation Liquid layer Liquid bridge

The ultimate goal of modeling—Simulation of system and plant performance

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Particuology 2011年第4期9卷 320-329页

作者： Joachim Werther stefan heinrich Maksym Dosta Ernst-Ulrich Hartge Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Modern production processes in chemical, pharmaceutical and biological industries are characterized by complex process structures, which consist of different apparatuses and process steps. Modeling the entire process requires simulating all units altogether, while taking into account interconnections between them, Nevertheless, in the area of solids processing, there is nowadays an unfilled gap from the side of computer support of process modeling in allowing effective optimization and prediction of the behavior of the whole plant, This paper presents a tool for flowsheet simulation which allows the simulation of the stationary behavior of complex processes dealing with solids and its extension towards dynamic modeling, Also, a new simulation concept is proposed on the basis of the multiscale approach. On the macroscale, fiowsheet simulation is performed with the help of the SolidSim system. Parameters for the macromodels in Solid-Sim are predicted by microscale simulation. The models for the two scales are then coupled by inter-scale communication laws. Application of the proposed modeling concept is shown by an example of fluidized bed granulation.

关键词： Flowsheet simulation Multiscale modeling Plant performance Solids processes Granulation