Sizing Wet-Gas Pipelines and Slug Catchers With Steady-State Multiphase Flow Simulations

1998 ◽  
Vol 120 (2) ◽  
pp. 106-110 ◽  
Author(s):  
J. J. Xiao ◽  
G. Shoup
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Simulation Models ◽  
Gas Pipelines ◽  
Flow Simulations ◽  
Wet Gas ◽  
Starting Point ◽  
Operational Information ◽  
Exit Speed ◽  
Steady State Simulation

The design of wet-gas pipelines and slug catchers requires multiphase flow simulations, both steady-state and transient. However, steady-state simulation is often inadequately conducted and its potential not fully utilized. This paper shows how mechanistic steady-state simulation models can be used to obtain not only pressure drop, liquid holdup and flow regime, but also to extract important operational information such as pig transit time, pig exit speed, liquid buildup rate behind the pig, and the time for the pipeline to return to a steady-state after pigging. A well-designed set of steady-state simulations helps to determine pipeline size, slug catcher size, and pigging frequency. It also serves as a starting point for subsequent transient multiphase flow simulations.

Requirements of Pipeline Simulation: Accurately Modeling Transient Pipeline Operation

1998 ◽  
Author(s):  
Kenneth H. Hanks ◽  
Galen T. Stanley
Keyword(s):  
Computer Technology ◽  
Single Phase ◽  
Simulation Models ◽  
Inventory Analysis ◽  
Two Phase ◽  
Operator Training ◽  
Wet Gas ◽  
Hydraulic Conditions ◽  
Steady State Simulation ◽  
Pipeline Design

In an attempt simulate the hydraulic conditions actually exhibited in a pipeline, several simplifications have traditionally been made to reduce the computational requirements and complexity of the simulation models. Recent advances in computer technology and solution techniques have allowed many of these simplifications to be removed. This paper discusses the benefit of the proper simulation of several of these areas. Transient vs. Steady state simulation, Two-phase vs. Single-phase simulation, Newtonian vs. Non-Newtonian fluid flow, Multi-component boiling and condensation in wet gas. The effects of these features on leak detection, line pack, pressure loss, and inventory analysis are discussed, as well as the effects on pipeline design, operator training, and real time decision support.

Change in Distillation Column Control Philosophy Using Dynamic Simulation

2019 ◽  
Vol 15 (3) ◽  
Author(s):  
Kanubhai Parmar ◽  
Sukanta Dash ◽  
Sunil Patil ◽  
Garimella Padmavathi
Keyword(s):  
Steady State ◽  
Dynamic Simulation ◽  
Operating Parameter ◽  
Simulation Models ◽  
Composition Control ◽  
Aspen Hysys ◽  
Steady State Model ◽  
Process Behavior ◽  
Steady State Simulation ◽  
Bottom Product

AbstractAt condensate stripper of a cracker plant with design control philosophy for composition control pant was facing operational difficulty. Due to disturbance in operating parameter column was becoming unstable and product was getting offspec w.r.t. desired purity. One of the applications of dynamic simulation is to troubleshoot the challenges related to control philosophy in practical application. Since steady-state simulation models cannot predict behavior with respect to time, initially steady state model and finally a dynamic model was developed in Aspen HYSYS. The model is used to study the process behavior for existing control philosophy and proposed philosophy. To avoid column puncture and without waiting for plant shut down the existing Temperature Indicator (TI) considered as Temperature Indicator Controller (TIC) for the study. A new control philosophy was developed based on the response of variables after disturbances in feed rate and composition. The revised control philosophy has been implemented and is now working satisfactorily, providing stabilized operation of the column with consistent bottom product quality. This has helped to reduce the loss of C2s in the bottom stream by about 700 ppm, for savings of about $100,000 USD per year.

scholarly journals Generalizing WDN simulation models to variable tank levels

2011 ◽  
Vol 14 (3) ◽  
pp. 562-573 ◽  
Author(s):  
Orazio Giustolisi ◽  
Luigi Berardi ◽  
Daniele Laucelli
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Water Distribution ◽  
Extended Period ◽  
Water Distribution Network ◽  
Simulation Models ◽  
Gradient Algorithm ◽  
Initial State ◽  
Cross Sectional ◽  
Steady State Simulation

In water distribution network (WDN) steady-state modelling, tanks and reservoirs are modelled as nodes with known heads. As a result, the tank levels are upgraded after every steady-state simulation (snapshot) using external mass balance equations in extended period simulation (EPS). This approach can give rise to numerical instabilities, especially when tanks are in close proximity. In order to obtain a stable EPS model, an unsteady formulation of the WDN model has recently introduced. This work presents an extension of the steady-state WDN model, both for demand-driven and pressure-driven analyses, allowing the direct prediction of head variation of tank nodes with respect to an initial state. Head variations at those nodes are introduced as internal unknowns in the model, the variation of tank levels can be analyzed in the single steady-state simulation and EPS can be performed as a sequence of simulations without the need for external mass balances. The extension of mass balance at tank nodes allows the analysis of some technically relevant demand components. Furthermore, inlet and outlet head losses at tank nodes are introduced and large cross-sectional tank areas are allowed by the model and reservoirs become a special case of tanks. The solution algorithm is the generalized-global gradient algorithm (G-GGA), although the proposed WDN model generalization is universal.

scholarly journals Guidelines to Calibrate a Multi-Residential Building Simulation Model Addressing Overheating Evaluation and Residents’ Influence

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 242
Author(s):  
Christoph Schünemann ◽  
David Schiela ◽  
Regine Ortlepp
Keyword(s):  
Simulation Model ◽  
Time Window ◽  
Residential Building ◽  
Simulation Models ◽  
Building Simulation ◽  
Night Time ◽  
Building Performance Simulation ◽  
Starting Point ◽  
3D Simulation Model ◽  
Building Physics

Can building performance simulation reproduce measured summertime indoor conditions of a multi-residential building in good conformity? This question is answered by calibrating simulated to monitored room temperatures of several rooms of a multi-residential building for an entire summer in two process steps. First, we did a calibration for several days without the residents being present to validate the building physics of the 3D simulation model. Second, the simulations were calibrated for the entire summer period, including the residents’ impact on evolving room temperature and overheating. As a result, a high degree of conformity between simulation and measurement could be achieved for all monitored rooms. The credibility of our results was secured by a detailed sensitivity analysis under varying meteorological conditions, shading situations, and window ventilation or room use in the simulation model. For top floor dwellings, a high overheating intensity was evoked by a combination of insufficient use of night-time window ventilation and non-heat-adapted residential behavior in combination with high solar gains and low heat storage capacities. Finally, the overall findings were merged into a process guideline to describe how a step-by-step calibration of residential building simulation models can be done. This guideline is intended to be a starting point for future discussions about the validity of the simplified boundary conditions which are often used in present-day standard overheating assessment.

Cyclic Breathing Simulations in Large Scale Models of the Lung Airway From the Oronasal Opening to the Terminal Bronchioles

2012 ◽  
Author(s):  
D. Keith Walters ◽  
Greg W. Burgreen ◽  
Robert L. Hester ◽  
David S. Thompson ◽  
David M. Lavallee ◽  
...  
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Large Scale ◽  
Whole Body ◽  
Patient Specific ◽  
Cfd Simulations ◽  
Reduced Order ◽  
Scale Models ◽  
Steady State Simulation ◽  
Conducting Zone

Computational fluid dynamics (CFD) simulations were performed for unsteady periodic breathing conditions, using large-scale models of the human lung airway. The computational domain included fully coupled representations of the orotracheal region and large conducting zone up to generation four (G4) obtained from patient-specific CT data, and the small conducting zone (to G16) obtained from a stochastically generated airway tree with statistically realistic geometrical characteristics. A reduced-order geometry was used, in which several airway branches in each generation were truncated, and only select flow paths were retained to G16. The inlet and outlet flow boundaries corresponded to the oronasal opening (superior), the inlet/outlet planes in terminal bronchioles (distal), and the unresolved airway boundaries arising from the truncation procedure (intermediate). The cyclic flow was specified according to the predicted ventilation patterns for a healthy adult male at three different activity levels, supplied by the whole-body modeling software HumMod. The CFD simulations were performed using Ansys FLUENT. The mass flow distribution at the distal boundaries was prescribed using a previously documented methodology, in which the percentage of the total flow for each boundary was first determined from a steady-state simulation with an applied flow rate equal to the average during the inhalation phase of the breathing cycle. The distal pressure boundary conditions for the steady-state simulation were set using a stochastic coupling procedure to ensure physiologically realistic flow conditions. The results show that: 1) physiologically realistic flow is obtained in the model, in terms of cyclic mass conservation and approximately uniform pressure distribution in the distal airways; 2) the predicted alveolar pressure is in good agreement with previously documented values; and 3) the use of reduced-order geometry modeling allows accurate and efficient simulation of large-scale breathing lung flow, provided care is taken to use a physiologically realistic geometry and to properly address the unsteady boundary conditions.

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