Numerical Bifurcation Techniques for Chemical Reactor Problems

Three series of tracer studies were performed on three constructed wetlands at the New Hanover County Landfill near Wilmington, North Carolina, USA. One vegetated free water surface wetland (FWS-R), one vegetated subsurface flow wetland (SSF-R), and one unvegetated control subsurface flow wetland (SSF-C) were studied. A conservative tracer, lithium chloride, was used to study the chemical reactor behavior of these wetlands under normal operating conditions. Results indicated that short-circuiting is quite common in SSF wetlands, while FWS wetlands are well-mixed and not as subject to short-circuiting. These results were obtained from and reinforced with tracer measurements at interior points in these wetlands, analysis of residence time distributions from two different formulations, and the construction of residence volume distributions. The short-circuiting in the SSF wetlands can be attributed to the following: (1) Vertical mixing is inhibited by a combination of physical barriers and density gradients caused by rainfall and runoff dilution of the upper layer; and (2) Leachate is drawn from the bottom of the wetland, causing it to further prefer a flow path along the bottom.

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Enhanced Composite Nonlinear Control Technique using Adaptive Control for Nonlinear Delayed Systems

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2213111607666181226151059 ◽

2020 ◽

Vol 13 (3) ◽

pp. 396-404

Author(s):

Sonal Singh ◽

Shubhi Purwar

Keyword(s):

Adaptive Control ◽

Actuator Saturation ◽

Input Saturation ◽

Chemical Reactor ◽

Control Technique ◽

Control Law ◽

Nonlinear Feedback ◽

Composite Nonlinear Feedback ◽

Delayed Systems ◽

Analysis Of Stability

Background and Introduction: The proposed control law is designed to provide fast reference tracking with minimal overshoot and to minimize the effect of unknown nonlinearities and external disturbances. Methods: In this work, an enhanced composite nonlinear feedback technique using adaptive control is developed for a nonlinear delayed system subjected to input saturation and exogenous disturbances. It ensures that the plant response is not affected by adverse effect of actuator saturation, unknown time delay and unknown nonlinearities/ disturbances. The analysis of stability is done by Lyapunov-Krasovskii functional that guarantees asymptotical stability. Results: The proposed control law is validated by its implementation on exothermic chemical reactor. MATLAB figures are provided to compare the results. Conclusion: The simulation results of the proposed controller are compared with the conventional composite nonlinear feedback control which illustrates the efficiency of the proposed controller.

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Temperature control in a chemical reactor through variable area of the heat transfer surface. Experimental verification

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19820446 ◽

1982 ◽

Vol 47 (2) ◽

pp. 446-453

Author(s):

Josef Horák ◽

František Jiráček ◽

Libuše Ježová

Keyword(s):

Batch Reactor ◽

Exothermic Reaction ◽

Chemical Reactor ◽

Open Loop ◽

Heat Transfer Surface ◽

Laboratory Reactor ◽

Hysteresis Control ◽

Relay With Hysteresis ◽

Rate Of Response ◽

The Ideal

A possibility has been tested in the paper of the feed back control of temperature of the reaction mixture in a batch reactor with an exothermic reaction through the variable area of the cooling surface. The measurement were carried out in a laboratory reactor with a retractable cooler which was being immersed into the reaction mixture. The speed of motion of the cooler was sufficiently high permitting the process of immersion to be regarded as practically instantaneous. The aim of the control was to stabilize the set point temperature of the reaction mixture by a two-point controler. In dependence on the rate of response of the system to a change of the section variable either the ideal relay or the relay with hysteresis control algorithmus were used. The results of measurements showed that with the aid of a retractable cooler the temperature could be controlled safely even in those cases, in which the control by the variable flow rate of the coolant was unfeasible. The verification was carried out in the open-loop instable operating point of the reactor.

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Temperature control in a chemical reactor through variable area of the heat transfer surface. Simulation analysis

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19820430 ◽

1982 ◽

Vol 47 (2) ◽

pp. 430-445

Author(s):

Josef Horák ◽

Zina Valášková

Keyword(s):

Heat Exchange ◽

Simulation Analysis ◽

Batch Reactor ◽

Chemical Reactor ◽

Rate Of Change ◽

Action Variable ◽

Heat Exchange Surface ◽

Relay With Hysteresis ◽

Exchange Surface

An algorithm has been developed and on a mathematical model analyzed to stabilize the reaction temperature of a batch reactor. The reaction has been a zero-order one and the reactor has been operated in a instable operating point. The action variable is the heat exchange surface whose area is increased if the temperature is above, or decreased if the temperature is below the set point. The following two-point regulators have been studied: An ideal relay, a relay with hysteresis and an asymmetric PD relay. The effect has been discussed of the parameters of the regulators on the quality of regulation. Stability analysis has been made of the stationary switching cycles and the domains of applicability have been determined for individual regulators with respect to the rate of change of the area of heat exchange surface.

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Large qualitative models of complex chemical and bioengineering processes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19912107 ◽

1991 ◽

Vol 56 (10) ◽

pp. 2107-2141 ◽

Cited By ~ 5

Author(s):

Mirko Dohnal

Keyword(s):

Case Studies ◽

Chemical Process ◽

Ad Hoc ◽

Chemical Reactor ◽

Theoretical Background ◽

Qualitative Model ◽

Complex Chemical ◽

Practical Applications ◽

Qualitative Models ◽

Decomposition Principle

Qualitative model is a theoretical background of commonsense. Complex qualitative models can have prohibitively many solutions (qualitative states). Therefore a qualitative analogy of such classical quantitative tools as e.g. the decomposition is developed. Practical applications of decomposition principle is nearly always ad hoc. Therefore two case studies are presented in details, a chemical process (mixer, chemical reactor, separator) and an anaerobic fermentor.

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