scholarly journals Dynamic Simulation of Continuous Catalytic Reforming Process Based on Simultaneous Solution

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1347
Author(s):  
Hanyu Zhang ◽  
Weijie Zhao ◽  
Aipeng Jiang ◽  
Qiu-Yun Huang ◽  
Haokun Wang ◽  
...  

The dynamic simulation of the continuous catalytic reforming process is of great significance to the performance prediction and optimization of the entire process. In this study, a 34-lumped mechanism model described by differential algebra was established based on the actual process conditions of the continuous catalytic reforming process in China, and an efficient dynamic simulation solution method based on simultaneous equations was proposed. First, a 34-lumped differential–algebraic mechanism model was established based on the basic principles of reforming kinetics, thermodynamics, material balance, and energy balance. Secondly, in order to solve and simulate the mechanism model composed of 144 differential equations and several algebraic equations, the method of finite-element collocation is used to discretize the differential equations and convert them into large-scale, nonlinear programming problems, and the interior point algorithm is used to estimate its parameters and verify the model. In addition, in order to avoid the problem of too long derivative solution time and too large memory in the solution process, methods such as sparse derivative and Broyden–Fletcher–Goldfarb–Shanno (BFGS) with limited storage are used to solve the problem. Finally, on the basis of model verification, dynamic simulation and sensitivity analysis of the whole process are carried out by modifying different input parameters. The results show that the mechanism model and solution method presented in this paper can quickly and accurately simulate the continuous catalytic reforming process dynamically.

2016 ◽  
Vol 49 (7) ◽  
pp. 615-620 ◽  
Author(s):  
Alistair D. Rodman ◽  
Dimitrios I. Gerogiorgis

2013 ◽  
Vol 5 (03) ◽  
pp. 269-308 ◽  
Author(s):  
M. Aminbaghai ◽  
M. Dorn ◽  
J. Eberhardsteiner ◽  
B. Pichler

AbstractMany problems in engineering sciences can be described by linear, inhomogeneous,m-th order ordinary differential equations (ODEs) with variable coefficients. For this wide class of problems, we here present a new, simple, flexible, and robust solution method, based on piecewise exact integration of local approximation polynomials as well as on averaging local integrals. The method is designed for modern mathematical software providing efficient environments for numerical matrix-vector operation-based calculus. Based on cubic approximation polynomials, the presented method can be expected to perform (i) similar to the Runge-Kutta method, when applied to stiff initial value problems, and (ii) significantly better than the finite difference method, when applied to boundary value problems. Therefore, we use the presented method for the analysis of engineering problems including the oscillation of a modulated torsional spring pendulum, steady-state heat transfer through a cooling web, and the structural analysis of a slender tower based on second-order beam theory. Related convergence studies provide insight into the satisfying characteristics of the proposed solution scheme.


2010 ◽  
Vol 2010 ◽  
pp. 1-15
Author(s):  
Piao-Piao Shi ◽  
Wen-Xia Wang

We investigate the infinite boundary value problems for second-order impulsive differential equations with supremum by establishing a new comparison result and using the lower and upper solution method, and obtain the existence results for their maximal and minimal solutions.


2004 ◽  
Vol 15 (03) ◽  
pp. 535-554 ◽  
Author(s):  
THOMAS RAUBER ◽  
GUDULA RÜNGER

Numerical software for sequential or parallel machines with memory hierarchies can benefit from locality optimizations which are usually achieved by program restructuring or program transformations. In this paper we introduce and discuss program-based locality measures which can be used to guide the restructuring and transformation process at program level. As example we consider a popular solution method to solve ordinary differential equations provided in many scientific libraries.


Author(s):  
Aki M. Mikkola

Abstract Welded structures, such as hydraulically driven booms, are disposed to fatigue damage. Design against fatigue requires information on the fatigue resistance of a structure’s critical details and the fatigue loads that act on each detail. The present paper introduces a method based on dynamic simulation for determining the fatigue loads in a hydraulically driven log crane. The detailed simulation model was built up in the MBS-software environment in which the flexible mechanism model and the equations describing the hydraulic system were combined. The complete simulation model was verified by comparing measurements to numerical results. This comparison shows that there is a clear correspondence between the simulated and measured results. It was thus shown that it is possible to create a simulation model which can be used realistically for determining stresses in fatigue analysis. The model was employed in the study of the fatigue loads, which are formed when the crane is being loaded.


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