Analysis of the Steady-State Multiplicity Behavior for Polystyrene Production in the CSTR

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Sang Thanh Nguyen ◽  
Ngoc Ha Hoang ◽  
Mohamed Azlan Hussain
Keyword(s):  
Heat Balance ◽  
Phase Plane ◽  
Volumetric Flow Rate ◽  
Operating Conditions ◽  
Continuous Stirred Tank Reactor ◽  
Styrene Polymerization ◽  
Wide Range ◽  
Continuous Stirred Tank ◽  
State Multiplicity ◽  
Bifurcation Behavior

Abstract The work proposes two different approaches where the first one is based on the tools of the system theory and the other is strongly related to the principle of heat balance, in order to analyze the abnormal phenomena of the continuous styrene polymerization reactors, i. e. the multiplicity behavior in the wide range of operating conditions. More precisely, the multiplicity behavior of polystyrene production in a continuous stirred tank reactor (CSTR) is carried out by the numerical simulations through the Van Heerden diagram and the phase plane. Furthermore, the bifurcation diagrams in terms of two different inputs including jacket temperature and volumetric flow rate of initiator predict the appearance of multiplicity behavior as well as the saddle-node bifurcation points. The results, firstly, verify that the multiplicity behavior of the system appears under considered operating conditions. Secondly, the analysis of bifurcation behavior gives the theoretical prediction of multiplicity behavior once the operating conditions vary due to the soft constraints or the effect of noise and disturbance.

scholarly journals Novel Multiplicity and Stability Criteria for Non-Isothermal Fixed-Bed Reactors

2021 ◽  
Vol 8 ◽  
Author(s):  
Jens Bremer ◽  
Kai Sundmacher
Keyword(s):  
Exothermic Reaction ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Continuous Stirred Tank Reactor ◽  
Stability Criteria ◽  
Fixed Bed Reactors ◽  
Continuous Stirred Tank ◽  
Back Mixing ◽  
State Multiplicity ◽  
New Criteria

With the increasing need to utilize carbon dioxide, fixed-bed reactors for catalytic hydrogenation will become a decisive element for modern chemicals and energy carrier production. In this context, the resilience and flexibility to changing operating conditions become major objectives for the design and operation of real industrial-scale reactors. Therefore steady-state multiplicity and stability are essential measures, but so far, their quantification is primarily accessible for ideal reactor concepts with zero or infinite back-mixing. Based on a continuous stirred tank reactor cascade modeling approach, this work derives novel criteria for stability, multiplicity, and uniqueness applicable to real reactors with finite back-mixing. Furthermore, the connection to other reactor features such as runaway and parametric sensitivity is demonstrated and exemplified for CO2 methanation under realistic conditions. The new criteria indicate that thermo-kinetic multiplicities induced by back-mixing remain relevant even for high Bodenstein numbers. In consequence, generally accepted back-mixing criteria (e.g., Mears’ criterion) appear insufficient for real non-isothermal reactors. The criteria derived in this work are applicable to any exothermic reaction and reactors at any scale. Ignoring uniqueness and multiplicity would disregard a broad operating range and thus a substantial potential for reactor resilience and flexibility.

Optimization-Based Strategies for Grade Transition Operation of a Continuous Styrene Polymerization Process

2011 ◽  
Vol 48-49 ◽  
pp. 798-801
Author(s):  
Qing Guo ◽  
Hua Qing Wang ◽  
Wei Guo Lin ◽  
Jian Feng Yang
Keyword(s):  
Control System ◽  
Transition Time ◽  
Regulatory Control ◽  
Polymerization Process ◽  
Continuous Stirred Tank Reactor ◽  
Styrene Polymerization ◽  
Grade Transition ◽  
Quality Grade ◽  
Continuous Stirred Tank

We present a combination of feedforward and regulatory control system to implement optimal grade transition operation of a continuous stirred tank reactor (CSTR) that must produce several grades of polymers. When the target polymer quality grade is specified, a two-step approach is adopted to implement the optimal grade transition operation. The dynamic optimization is carried out to minimize the amount of initiator assumption during the transition operation as well as to shorten the transition time. Through case study of a free radical styrene polymerization, it is shown that both transition time and initiator assumption are superior to those of a regulatory control system.

The bifurcation behavior of a polyurethane continuous stirred tank reactor

2006 ◽  
Vol 61 (22) ◽  
pp. 7368-7385 ◽  
Author(s):  
Víctor Zavala-Tejeda ◽  
Antonio Flores-Tlacuahuac ◽  
Eduardo Vivaldo-Lima
Keyword(s):  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank ◽  
Bifurcation Behavior

scholarly journals Effect of nitrogen loading rate and alkalinity on partial nitritation in a continuous stirred tank reactor

2021 ◽  
Vol 27 (1) ◽  
pp. 200573-0
Author(s):  
Daehee Choi ◽  
Thanh Phuong To ◽  
Wonsang Yun ◽  
Dongjin Ju ◽  
Keugtae Kim ◽  
...  
Keyword(s):  
Loading Rate ◽  
Nitrogen Loading ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Ammonium Oxidation ◽  
Continuous Stirred Tank Reactor ◽  
Partial Nitritation ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank

In order to achieve an appropriate effluent ratio of ammonium and nitrite as an influent of the anaerobic ammonium oxidation process, the optimum conditions for the partial nitritation in a continuous stirred tank reactor (CSTR) were investigated using real reject water. Hydraulic retention time (HRT) and influent alkalinity (HCO3-)/NH4+-N ratio were major factors that greatly influenced the partial nitritation. As a result of continuous operation, ammonium conversion efficiency (ACE) and effluent nitrite to ammonium ratio (NAR) could be achieved at the HRT of 19 h corresponding to 0.71 kg/m3/d of nitrogen loading rate (NLR). Thereafter, the influent HCO3-/NH4+-N ratio was adjusted from 0.5 to 2, and as a result, the optimum partial nitritation efficiency was maintained when the influent HCO3-/NH4+-N ratio was one. The suitability of the determined operating conditions was verified in a CSTR over 30 d of operation time.

scholarly journals Simulating Trambouze reaction for a series reactor

2020 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Amizon Azizan ◽  
Nornizar Anuar
Keyword(s):  
Flow Rate ◽  
Coming Out ◽  
Flow Reactor ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Continuous Stirred Tank Reactor ◽  
Maximum Conversion ◽  
Outlet Stream ◽  
Continuous Stirred Tank ◽  
Flow Rate Influence

Simulating the existing data on Trambouze reaction is compiled in this article. The objective of the work is to present the change of volumetric flow rate and the inlet concentration of key reactant A in a series continuous stirred tank reactor-plug flow reactor (CSTR-PFR) configurations. The volumetric flow rate does not affect selectivity and conversion for a constant volumetric flow rate operating condition, entering CSTR and PFR, at a specific concentration of reactant. The CSTR-PFR series reactor configuration is proposed for the aim of maximizing the selectivity of the desired product B in comparison to the undesired products X and Y. CSTR as the first reactor is capable to achieve the maximum conversion at the highest selectivity of A. PFR is then proposed after CSTR in a configuration of CSTR-PFR, to allow higher conversion value to be achieved for the resulted outlet stream conditions coming out of the first reactor, CSTR. Both reactors commonly encounter a decrease in the initial concentration of A and an increase to the formation of other products. The CSTR entering volumetric flow rate influence the volume sizes needed in achieving the maximum selectivity and conversion

scholarly journals Conceptual Study of Transesterification of Vegetable Oils in the Continuous-Stirred-Tank Reactor at Unsteady-State and Isothermal Conditions

2021 ◽  
Vol 17 (2) ◽  
pp. 181-194
Author(s):  
Fadzil Noor Gonawan ◽  
Azlina Harun Kamaruddin
Keyword(s):  
Flow Rate ◽  
Enzymatic Reaction ◽  
Volumetric Flow Rate ◽  
Packed Bed ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Isothermal Conditions ◽  
Continuous Stirred Tank

The continuous-stirred-tank reactor (CSTR) is favorable for bi-phasic enzymatic reaction due to ease of operation, cost-effective and low downtime. Lack of study on the enzymatic reaction in the CSTR has disfavor this type of reactor compared to batch and packed bed. Presently, a simulation was carried out to simulate the behavior of the lipase-catalyzed production of biodiesel by using CSTR at isothermal conditions. The mathematical model incorporated the effect of the kinetic, thermal, and operating parameters. The parameters such as Michaelis constant (Km), inhibition constant (Ki), Gibbs inactivation energy (DelG) and mol flow rate are among determining factors of the course of the reaction. It is suggested that the enzyme with lower , higher , and higher  should be chosen for the reaction. In continuous operation in the CSTR, the volumetric flow rate of the substrates and the initial concentration of the feed could be used to control reaction performance as these parameters will determine the total mol or ratio of the substrates in the reactor. Most, importantly, the longer residence time is preferred to achieve higher conversion, however, the volumetric flow rate must not be too low to prevent underperformance of reaction.

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