Dynamic Optimization of the Tandem Acetylene Hydrogenation Process

Abstract

In ethylene production units, the acetylene side product is converted into additional C 2 H 4 over a palladium− carbon fixed bed reactor, in which the catalyst activity is affected by the formation of green oil impurities. We determined the optimal dynamic operating conditions for two reactors in series undergoing catalyst deactivation while maintaining the selectivity and conversion rate. The optimal switching periods for the reactors were investigated with dynamic optimization of the hydrogen input and inlet temperature with the incremental feature. Control vector parametrization was used to transform this dynamic problem into a finite-dimensional nonlinear programming problem. An incremental-encoding differential evolution with constraint ranking-based mutation operator (IEDE-CRMO) was proposed based on the reaction selectivity and catalyst activity variation to meet certain requirements of the control variables and to solve a complex industrial process. The IEDE-CRMO method was applied in an industrial C2 hydrogenation tandem reaction process, and results showed improvement in overall operation efficiency.

Quadratic Interpolation Based Simultaneous Heat Transfer Search Algorithm and Its Application to Chemical Dynamic System Optimization

“…In other words, if the time-independent undetermined parameters ρ exist, then it is a parameter estimation problem which can be directly translated into an NLP problem. While, if the time-dependent control variables u(t) exist, this problem is an optimal control problem which cannot be directly transformed into an NLP problem; thus, a discretization approach such as control vector parametrization (CVP) method [11,12] is required to translate it into an NLP problem. The time interval is divided by the CVP method into a number of stages (N), wherein the control variables u(t) in every sup-interval are approximated by means of basis functions, such as linear functions, constant functions, and wavelet-based functions.…”

“…Moreover, the computational results are compared with those of twelve well-established methods. Due to the existence of time-dependent control variables ( ) u t in these problems, a discretization approach such as the control vector parametrization (CVP) method [11,12] is utilized to discretize these problems. To be consistent with the reference, the time interval is divided by the CVP method into 20 stages with equal length, wherein the control variables ( ) u t in every supinterval are approximated by piece-linear functions.…”

“…The CP method can preferably deal with path constraint problems, but it results in a large-scale nonlinear programming (NLP) problem, and certain techniques are needed to solve the NLP efficiently. The CVP method is used to translate the basic DOP into an NLP problem; the dimension range of NLP problems in this method is much smaller than that in the CP method; therefore, the CVP method has been incorporated with various optimization algorithms to handle DOPs [11,12]. A number of deterministic methods have also been proposed for handling DOPs; the gradient-based methods [13,14], such as the sequence quadratic program and Newton's algorithms, are considered as deterministic methods that can converge rapidly.…”

Recent progress and challenges in process optimization: Review of recent work at ECUST

“…Chen et al presented a new method called ranking‐based mutation operator, and formulated as DE‐RMO, to enhance the DE algorithms and to solve DOPs based on control vector parameterization. Du et al proposed an incremental‐encoding differential evolution with a constraint ranking‐based mutation operator (IEDE‐CRMO) for the dynamic optimization of an industrial C2 hydrogenation tandem reaction process. Qian et al proposed an iterative genetic algorithm to solve the DOPs of chemical processes by introducing search region reduction in GA and approximating control variable trajectory with the high‐order polynomial.…”

CFD Simulation and Optimization of Adiabatic Reaction Process of C-2 Hydrogenation

“…Finally, step response characteristics of inlet temperature of the reactor and hydrogen/acetylene ratio of the feedstock were analyzed. Du et al (2017) [17] studied mainly the operating conditions of the two-stage tandem acetylene hydrogenation reactor. When the catalyst was in the state of dynamic inactivation, the optimal operating conditions of the system were given by taking the ethylene selectivity and acetylene conversion rate as the optimization objective.…”